17 files changed, 183 insertions, 138 deletions
diff --git a/guides/assets/images/rails_guides_logo_1x.png b/guides/assets/images/rails_guides_logo_1x.png
new file mode 100644
index 0000000000..8c6810c312
--- /dev/null
+++ b/guides/assets/images/rails_guides_logo_1x.png
diff --git a/guides/assets/images/rails_guides_logo_2x.png b/guides/assets/images/rails_guides_logo_2x.png
new file mode 100644
index 0000000000..accc6bbfa4
--- /dev/null
+++ b/guides/assets/images/rails_guides_logo_2x.png
diff --git a/guides/assets/stylesheets/main.css b/guides/assets/stylesheets/main.css
index 2657a84a91..bdc3e21977 100644
--- a/guides/assets/stylesheets/main.css
+++ b/guides/assets/stylesheets/main.css
@@ -401,14 +401,10 @@ a, a:link, a:visited {
 }
 
 #guides {
-  width: 27em;
+  width: 37em;
   display: block;
   background: #980905;
   border-radius: 1em;
-  -webkit-border-radius: 1em;
-  -moz-border-radius: 1em;
-  -webkit-box-shadow: 0.25em 0.25em 1em rgba(0,0,0,0.25);
-  -moz-box-shadow: rgba(0,0,0,0.25) 0.25em 0.25em 1em;
   color: #f1938c;
   padding: 1.5em 2em;
   position: absolute;
@@ -422,17 +418,44 @@ a, a:link, a:visited {
   display: block !important;
 }
 
-#guides dt, #guides dd {
+.guides-section dt, .guides-section dd {
   font-weight: normal;
   font-size: 0.722em;
   margin: 0;
   padding: 0;
 }
-#guides dt {padding:0; margin: 0.5em 0 0;}
-#guides a {color: #FFF; background: none !important; text-decoration: none;}
-#guides a:hover {text-decoration: underline;}
-#guides .L, #guides .R {float: left; width: 50%; margin: 0; padding: 0;}
-#guides .R {float: right;}
+.guides-section dt {
+  margin: 0.5em 0 0;
+  padding:0;
+}
+#guides a {
+  background: none !important;
+  color: #FFF;
+  text-decoration: none;
+}
+#guides a:hover {
+  text-decoration: underline;
+}
+.guides-section-container {
+  display: flex;
+  flex-direction: column;
+  flex-wrap: wrap;
+  width: 100%;
+  max-height: 35em;
+}
+
+.guides-section {
+  min-width: 5em;
+  margin: 0 2em 0.5em 0;
+  flex: auto;
+  max-width: 12em;
+}
+
+.guides-section dd {
+  line-height: 1.3;
+  margin-bottom: 0.5em;
+}
+
 #guides hr {
   display: block;
   border: none;
@@ -515,13 +538,26 @@ h6 {
 
 #header h1 {
   float: left;
-  background: url(../images/rails_guides_logo.gif) no-repeat;
+  background: url(../images/rails_guides_logo_1x.png) no-repeat;
   width: 297px;
   text-indent: -9999em;
   margin: 0;
   padding: 0;
 }
 
+@media
+only screen and (-webkit-min-device-pixel-ratio: 2),
+only screen and (   min--moz-device-pixel-ratio: 2),
+only screen and (     -o-min-device-pixel-ratio: 2/1),
+only screen and (        min-device-pixel-ratio: 2),
+only screen and (                min-resolution: 192dpi),
+only screen and (                min-resolution: 2dppx) {
+  #header h1 {
+    background: url(../images/rails_guides_logo_2x.png) no-repeat;
+    background-size: 160%;
+  }
+}
+
 @media screen and (max-width: 480px) {
   #header h1 {
     float: none;
diff --git a/guides/source/5_1_release_notes.md b/guides/source/5_1_release_notes.md
index d26d3d3b95..a5a7eb4b2e 100644
--- a/guides/source/5_1_release_notes.md
+++ b/guides/source/5_1_release_notes.md
@@ -399,7 +399,7 @@ Please refer to the [Changelog][action-view] for detailed changes.
 
 *   Change `datetime_field` and `datetime_field_tag` to generate `datetime-local`
     fields.
-    ([Pull Request](https://github.com/rails/rails/pull/28061))
+    ([Pull Request](https://github.com/rails/rails/pull/25469))
 
 *   New Builder-style syntax for HTML tags (`tag.div`, `tag.br`, etc.)
     ([Pull Request](https://github.com/rails/rails/pull/25543))
diff --git a/guides/source/action_controller_overview.md b/guides/source/action_controller_overview.md
index 43bc9306ce..aa746e4731 100644
--- a/guides/source/action_controller_overview.md
+++ b/guides/source/action_controller_overview.md
@@ -166,7 +166,7 @@ NOTE: Support for parsing XML parameters has been extracted into a gem named `ac
 The `params` hash will always contain the `:controller` and `:action` keys, but you should use the methods `controller_name` and `action_name` instead to access these values. Any other parameters defined by the routing, such as `:id`, will also be available. As an example, consider a listing of clients where the list can show either active or inactive clients. We can add a route which captures the `:status` parameter in a "pretty" URL:
 
 ```ruby
-get '/clients/:status' => 'clients#index', foo: 'bar'
+get '/clients/:status', to: 'clients#index', foo: 'bar'
 ```
 
 In this case, when a user opens the URL `/clients/active`, `params[:status]` will be set to "active". When this route is used, `params[:foo]` will also be set to "bar", as if it were passed in the query string. Your controller will also receive `params[:action]` as "index" and `params[:controller]` as "clients".
diff --git a/guides/source/action_mailer_basics.md b/guides/source/action_mailer_basics.md
index 041a427f7c..1acb993cad 100644
--- a/guides/source/action_mailer_basics.md
+++ b/guides/source/action_mailer_basics.md
@@ -839,13 +839,14 @@ Mailer Testing
 You can find detailed instructions on how to test your mailers in the
 [testing guide](testing.html#testing-your-mailers).
 
-Intercepting Emails
+Intercepting and Observing Emails
 -------------------
 
-There are situations where you need to edit an email before it's
-delivered. Fortunately Action Mailer provides hooks to intercept every
-email. You can register an interceptor to make modifications to mail messages
-right before they are handed to the delivery agents.
+Action Mailer provides hooks into the Mail observer and interceptor methods. These allow you to register classes that are called during the mail delivery life cycle of every email sent.
+
+### Intercepting Emails
+
+Interceptors allow you to make modifications to emails before they are handed off to the delivery agents. An interceptor class must implement the `:delivering_email(message)` method which will be called before the email is sent.
 
 ```ruby
 class SandboxEmailInterceptor
@@ -869,3 +870,21 @@ NOTE: The example above uses a custom environment called "staging" for a
 production like server but for testing purposes. You can read
 [Creating Rails environments](configuring.html#creating-rails-environments)
 for more information about custom Rails environments.
+
+### Observing Emails
+
+Observers give you access to the email message after it has been sent. An observer class must implement the `:delivered_email(message)` method, which will be called after the email is sent.
+
+```ruby
+class EmailDeliveryObserver
+  def self.delivered_email(message)
+    EmailDelivery.log(message)
+  end
+end
+```
+Like interceptors, you need to register observers with the Action Mailer framework. You can do this in an initializer file 
+`config/initializers/email_delivery_observer.rb`
+
+```ruby
+ActionMailer::Base.register_observer(EmailDeliveryObserver)
+```
diff --git a/guides/source/active_record_basics.md b/guides/source/active_record_basics.md
index fad4c19827..b9e24099b1 100644
--- a/guides/source/active_record_basics.md
+++ b/guides/source/active_record_basics.md
@@ -82,9 +82,9 @@ of two or more words, the model class name should follow the Ruby conventions,
 using the CamelCase form, while the table name must contain the words separated
 by underscores. Examples:
 
-* Database Table - Plural with underscores separating words (e.g., `book_clubs`).
 * Model Class - Singular with the first letter of each word capitalized (e.g.,
 `BookClub`).
+* Database Table - Plural with underscores separating words (e.g., `book_clubs`).
 
 | Model / Class    | Table / Schema |
 | ---------------- | -------------- |
diff --git a/guides/source/asset_pipeline.md b/guides/source/asset_pipeline.md
index 66cf9da33b..500e230ff9 100644
--- a/guides/source/asset_pipeline.md
+++ b/guides/source/asset_pipeline.md
@@ -233,11 +233,6 @@ code for JavaScript plugins and CSS frameworks. Keep in mind that third party
 code with references to other files also processed by the asset Pipeline (images,
 stylesheets, etc.), will need to be rewritten to use helpers like `asset_path`.
 
-WARNING: If you are upgrading from Rails 3, please take into account that assets
-under `lib/assets` or `vendor/assets` are available for inclusion via the
-application manifests but no longer part of the precompile array. See
-[Precompiling Assets](#precompiling-assets) for guidance.
-
 #### Search Paths
 
 When a file is referenced from a manifest or a helper, Sprockets searches the
@@ -1234,60 +1229,3 @@ it as a preprocessor for your mime type.
 Sprockets.register_preprocessor 'text/css', AddComment
 ```
 
-Upgrading from Old Versions of Rails
-------------------------------------
-
-There are a few issues when upgrading from Rails 3.0 or Rails 2.x. The first is
-moving the files from `public/` to the new locations. See [Asset
-Organization](#asset-organization) above for guidance on the correct locations
-for different file types.
-
-Next is updating the various environment files with the correct default
-options.
-
-In `application.rb`:
-
-```ruby
-# Version of your assets, change this if you want to expire all your assets
-config.assets.version = '1.0'
-
-# Change the path that assets are served from config.assets.prefix = "/assets"
-```
-
-In `development.rb`:
-
-```ruby
-# Expands the lines which load the assets
-config.assets.debug = true
-```
-
-And in `production.rb`:
-
-```ruby
-# Choose the compressors to use (if any)
-config.assets.js_compressor = :uglifier
-# config.assets.css_compressor = :yui
-
-# Don't fallback to assets pipeline if a precompiled asset is missed
-config.assets.compile = false
-
-# Generate digests for assets URLs.
-config.assets.digest = true
-
-# Precompile additional assets (application.js, application.css, and all
-# non-JS/CSS are already added)
-# config.assets.precompile += %w( admin.js admin.css )
-```
-
-Rails 4 and above no longer set default config values for Sprockets in `test.rb`, so
-`test.rb` now requires Sprockets configuration. The old defaults in the test
-environment are: `config.assets.compile = true`, `config.assets.compress = false`,
-`config.assets.debug = false` and `config.assets.digest = false`.
-
-The following should also be added to your `Gemfile`:
-
-```ruby
-gem 'sass-rails',   "~> 3.2.3"
-gem 'coffee-rails', "~> 3.2.1"
-gem 'uglifier'
-```
diff --git a/guides/source/association_basics.md b/guides/source/association_basics.md
index a2231c55d7..78a1f47407 100644
--- a/guides/source/association_basics.md
+++ b/guides/source/association_basics.md
@@ -109,7 +109,7 @@ class CreateBooks < ActiveRecord::Migration[5.0]
     end
 
     create_table :books do |t|
-      t.belongs_to :author, index: true
+      t.belongs_to :author
       t.datetime :published_at
       t.timestamps
     end
@@ -140,7 +140,7 @@ class CreateSuppliers < ActiveRecord::Migration[5.0]
     end
 
     create_table :accounts do |t|
-      t.belongs_to :supplier, index: true
+      t.belongs_to :supplier
       t.string :account_number
       t.timestamps
     end
@@ -184,7 +184,7 @@ class CreateAuthors < ActiveRecord::Migration[5.0]
     end
 
     create_table :books do |t|
-      t.belongs_to :author, index: true
+      t.belongs_to :author
       t.datetime :published_at
       t.timestamps
     end
@@ -231,8 +231,8 @@ class CreateAppointments < ActiveRecord::Migration[5.0]
     end
 
     create_table :appointments do |t|
-      t.belongs_to :physician, index: true
-      t.belongs_to :patient, index: true
+      t.belongs_to :physician
+      t.belongs_to :patient
       t.datetime :appointment_date
       t.timestamps
     end
@@ -312,13 +312,13 @@ class CreateAccountHistories < ActiveRecord::Migration[5.0]
     end
 
     create_table :accounts do |t|
-      t.belongs_to :supplier, index: true
+      t.belongs_to :supplier
       t.string :account_number
       t.timestamps
     end
 
     create_table :account_histories do |t|
-      t.belongs_to :account, index: true
+      t.belongs_to :account
       t.integer :credit_rating
       t.timestamps
     end
@@ -358,8 +358,8 @@ class CreateAssembliesAndParts < ActiveRecord::Migration[5.0]
     end
 
     create_table :assemblies_parts, id: false do |t|
-      t.belongs_to :assembly, index: true
-      t.belongs_to :part, index: true
+      t.belongs_to :assembly
+      t.belongs_to :part
     end
   end
 end
@@ -487,7 +487,7 @@ class CreatePictures < ActiveRecord::Migration[5.0]
   def change
     create_table :pictures do |t|
       t.string :name
-      t.references :imageable, polymorphic: true, index: true
+      t.references :imageable, polymorphic: true
       t.timestamps
     end
   end
@@ -517,7 +517,7 @@ In your migrations/schema, you will add a references column to the model itself.
 class CreateEmployees < ActiveRecord::Migration[5.0]
   def change
     create_table :employees do |t|
-      t.references :manager, index: true
+      t.references :manager
       t.timestamps
     end
   end
@@ -868,7 +868,7 @@ While Rails uses intelligent defaults that will work well in most situations, th
 
 ```ruby
 class Book < ApplicationRecord
-  belongs_to :author, dependent: :destroy,
+  belongs_to :author, touch: :books_updated_at,
     counter_cache: true
 end
 ```
@@ -1048,8 +1048,7 @@ There may be times when you wish to customize the query used by `belongs_to`. Su
 
 ```ruby
 class Book < ApplicationRecord
-  belongs_to :author, -> { where active: true },
-                        dependent: :destroy
+  belongs_to :author, -> { where active: true }
 end
 ```
 
diff --git a/guides/source/configuring.md b/guides/source/configuring.md
index 812565b207..61bb35cf93 100644
--- a/guides/source/configuring.md
+++ b/guides/source/configuring.md
@@ -200,8 +200,6 @@ The full set of methods that can be used in this block are as follows:
 * `helper` defines whether or not to generate helpers. Defaults to `true`.
 * `integration_tool` defines which integration tool to use to generate integration tests. Defaults to `:test_unit`.
 * `system_tests` defines which integration tool to use to generate system tests. Defaults to `:test_unit`.
-* `javascripts` turns on the hook for JavaScript files in generators. Used in Rails for when the `scaffold` generator is run. Defaults to `true`.
-* `javascript_engine` configures the engine to be used (for eg. coffee) when generating assets. Defaults to `:js`.
 * `orm` defines which orm to use. Defaults to `false` and will use Active Record by default.
 * `resource_controller` defines which generator to use for generating a controller when using `rails generate resource`. Defaults to `:controller`.
 * `resource_route` defines whether a resource route definition should be generated
diff --git a/guides/source/debugging_rails_applications.md b/guides/source/debugging_rails_applications.md
index 88d205e1ab..7f7766e7d7 100644
--- a/guides/source/debugging_rails_applications.md
+++ b/guides/source/debugging_rails_applications.md
@@ -186,14 +186,17 @@ end
 Here's an example of the log generated when this controller action is executed:
 
 ```
-Started POST "/articles" for 127.0.0.1 at 2017-08-20 20:53:10 +0900
+Started POST "/articles" for 127.0.0.1 at 2018-10-18 20:09:23 -0400
 Processing by ArticlesController#create as HTML
-  Parameters: {"utf8"=>"✓", "authenticity_token"=>"xhuIbSBFytHCE1agHgvrlKnSVIOGD6jltW2tO+P6a/ACjQ3igjpV4OdbsZjIhC98QizWH9YdKokrqxBCJrtoqQ==", "article"=>{"title"=>"Debugging Rails", "body"=>"I'm learning how to print in logs!!!", "published"=>"0"}, "commit"=>"Create Article"}
-New article: {"id"=>nil, "title"=>"Debugging Rails", "body"=>"I'm learning how to print in logs!!!", "published"=>false, "created_at"=>nil, "updated_at"=>nil}
+  Parameters: {"utf8"=>"✓", "authenticity_token"=>"XLveDrKzF1SwaiNRPTaMtkrsTzedtebPPkmxEFIU0ordLjICSnXsSNfrdMa4ccyBjuGwnnEiQhEoMN6H1Gtz3A==", "article"=>{"title"=>"Debugging Rails", "body"=>"I'm learning how to print in logs.", "published"=>"0"}, "commit"=>"Create Article"}
+New article: {"id"=>nil, "title"=>"Debugging Rails", "body"=>"I'm learning how to print in logs.", "published"=>false, "created_at"=>nil, "updated_at"=>nil}
 Article should be valid: true
-   (0.1ms)  BEGIN
-  SQL (0.4ms)  INSERT INTO "articles" ("title", "body", "published", "created_at", "updated_at") VALUES ($1, $2, $3, $4, $5) RETURNING "id"  [["title", "Debugging Rails"], ["body", "I'm learning how to print in logs!!!"], ["published", "f"], ["created_at", "2017-08-20 11:53:10.010435"], ["updated_at", "2017-08-20 11:53:10.010435"]]
-   (0.3ms)  COMMIT
+   (0.0ms)  begin transaction
+  ↳ app/controllers/articles_controller.rb:31
+  Article Create (0.5ms)  INSERT INTO "articles" ("title", "body", "published", "created_at", "updated_at") VALUES (?, ?, ?, ?, ?)  [["title", "Debugging Rails"], ["body", "I'm learning how to print in logs."], ["published", 0], ["created_at", "2018-10-19 00:09:23.216549"], ["updated_at", "2018-10-19 00:09:23.216549"]]
+  ↳ app/controllers/articles_controller.rb:31
+   (2.3ms)  commit transaction
+  ↳ app/controllers/articles_controller.rb:31
 The article was saved and now the user is going to be redirected...
 Redirected to http://localhost:3000/articles/1
 Completed 302 Found in 4ms (ActiveRecord: 0.8ms)
@@ -201,6 +204,40 @@ Completed 302 Found in 4ms (ActiveRecord: 0.8ms)
 
 Adding extra logging like this makes it easy to search for unexpected or unusual behavior in your logs. If you add extra logging, be sure to make sensible use of log levels to avoid filling your production logs with useless trivia.
 
+### Verbose Query Logs
+
+When looking at database query output in logs, it may not be immediately clear why multiple database queries are triggered when a single method is called:
+
+```
+irb(main):001:0> Article.pamplemousse
+  Article Load (0.4ms)  SELECT "articles".* FROM "articles"
+  Comment Load (0.2ms)  SELECT "comments".* FROM "comments" WHERE "comments"."article_id" = ?  [["article_id", 1]]
+  Comment Load (0.1ms)  SELECT "comments".* FROM "comments" WHERE "comments"."article_id" = ?  [["article_id", 2]]
+  Comment Load (0.1ms)  SELECT "comments".* FROM "comments" WHERE "comments"."article_id" = ?  [["article_id", 3]]
+=> #<Comment id: 2, author: "1", body: "Well, actually...", article_id: 1, created_at: "2018-10-19 00:56:10", updated_at: "2018-10-19 00:56:10">
+```
+
+After running `ActiveRecord::Base.verbose_query_logs = true` in the `rails console` session to enable verbose query logs and running the method again, it becomes obvious what single line of code is generating all these discrete database calls:
+
+```
+irb(main):003:0> Article.pamplemousse
+  Article Load (0.2ms)  SELECT "articles".* FROM "articles"
+  ↳ app/models/article.rb:5
+  Comment Load (0.1ms)  SELECT "comments".* FROM "comments" WHERE "comments"."article_id" = ?  [["article_id", 1]]
+  ↳ app/models/article.rb:6
+  Comment Load (0.1ms)  SELECT "comments".* FROM "comments" WHERE "comments"."article_id" = ?  [["article_id", 2]]
+  ↳ app/models/article.rb:6
+  Comment Load (0.1ms)  SELECT "comments".* FROM "comments" WHERE "comments"."article_id" = ?  [["article_id", 3]]
+  ↳ app/models/article.rb:6
+=> #<Comment id: 2, author: "1", body: "Well, actually...", article_id: 1, created_at: "2018-10-19 00:56:10", updated_at: "2018-10-19 00:56:10">
+```
+
+Below each database statement you can see arrows pointing to the specific source filename (and line number) of the method that resulted in a database call. This can help you identity and address performance problems caused by N+1 queries: single database queries that generates multiple additional queries.
+
+Verbose query logs are enabled by default in the development environment logs after Rails 5.2.
+
+WARNING: We recommend against using this setting in production environments. It relies on Ruby's `Kernel#caller` method which tends to allocate a lot of memory in order to generate stacktraces of method calls.
+
 ### Tagged Logging
 
 When running multi-user, multi-account applications, it's often useful
diff --git a/guides/source/documents.yaml b/guides/source/documents.yaml
index 8f2312458d..551179c523 100644
--- a/guides/source/documents.yaml
+++ b/guides/source/documents.yaml
@@ -173,7 +173,7 @@
       description: This guide describes the considerations needed and tools available when working directly with concurrency in a Rails application.
       work_in_progress: true
 -
-  name: Contributing to Ruby on Rails
+  name: Contributions
   documents:
     -
       name: Contributing to Ruby on Rails
@@ -184,14 +184,14 @@
       url: api_documentation_guidelines.html
       description: This guide documents the Ruby on Rails API documentation guidelines.
     -
-      name: Ruby on Rails Guides Guidelines
+      name: Guides Guidelines
       url: ruby_on_rails_guides_guidelines.html
       description: This guide documents the Ruby on Rails guides guidelines.
 -
-  name: Maintenance Policy
+  name: Policies
   documents:
     -
-      name: Maintenance Policy for Ruby on Rails
+      name: Maintenance Policy
       url: maintenance_policy.html
       description: What versions of Ruby on Rails are currently supported, and when to expect new versions.
 -
@@ -202,51 +202,51 @@
       url: upgrading_ruby_on_rails.html
       description: This guide helps in upgrading applications to latest Ruby on Rails versions.
     -
-      name: Ruby on Rails 6.0 Release Notes
+      name: 6.0 Release Notes
       work_in_progress: true
       url: 6_0_release_notes.html
       description: Release notes for Rails 6.0.
     -
-      name: Ruby on Rails 5.2 Release Notes
+      name: 5.2 Release Notes
       url: 5_2_release_notes.html
       description: Release notes for Rails 5.2.
     -
-      name: Ruby on Rails 5.1 Release Notes
+      name: 5.1 Release Notes
       url: 5_1_release_notes.html
       description: Release notes for Rails 5.1.
     -
-      name: Ruby on Rails 5.0 Release Notes
+      name: 5.0 Release Notes
       url: 5_0_release_notes.html
       description: Release notes for Rails 5.0.
     -
-      name: Ruby on Rails 4.2 Release Notes
+      name: 4.2 Release Notes
       url: 4_2_release_notes.html
       description: Release notes for Rails 4.2.
     -
-      name: Ruby on Rails 4.1 Release Notes
+      name: 4.1 Release Notes
       url: 4_1_release_notes.html
       description: Release notes for Rails 4.1.
     -
-      name: Ruby on Rails 4.0 Release Notes
+      name: 4.0 Release Notes
       url: 4_0_release_notes.html
       description: Release notes for Rails 4.0.
     -
-      name: Ruby on Rails 3.2 Release Notes
+      name: 3.2 Release Notes
       url: 3_2_release_notes.html
       description: Release notes for Rails 3.2.
     -
-      name: Ruby on Rails 3.1 Release Notes
+      name: 3.1 Release Notes
       url: 3_1_release_notes.html
       description: Release notes for Rails 3.1.
     -
-      name: Ruby on Rails 3.0 Release Notes
+      name: 3.0 Release Notes
       url: 3_0_release_notes.html
       description: Release notes for Rails 3.0.
     -
-      name: Ruby on Rails 2.3 Release Notes
+      name: 2.3 Release Notes
       url: 2_3_release_notes.html
       description: Release notes for Rails 2.3.
     -
-      name: Ruby on Rails 2.2 Release Notes
+      name: 2.2 Release Notes
       url: 2_2_release_notes.html
       description: Release notes for Rails 2.2.
diff --git a/guides/source/generators.md b/guides/source/generators.md
index f028d14998..88ce4be8da 100644
--- a/guides/source/generators.md
+++ b/guides/source/generators.md
@@ -219,7 +219,7 @@ If we want to avoid generating the default `app/assets/stylesheets/scaffolds.scs
   end
 ```
 
-The next customization on the workflow will be to stop generating stylesheet, JavaScript, and test fixture files for scaffolds altogether. We can achieve that by changing our configuration to the following:
+The next customization on the workflow will be to stop generating stylesheet and test fixture files for scaffolds altogether. We can achieve that by changing our configuration to the following:
 
 ```ruby
 config.generators do |g|
@@ -227,7 +227,6 @@ config.generators do |g|
   g.template_engine :erb
   g.test_framework  :test_unit, fixture: false
   g.stylesheets     false
-  g.javascripts     false
 end
 ```
 
@@ -285,7 +284,6 @@ config.generators do |g|
   g.template_engine :erb
   g.test_framework  :test_unit, fixture: false
   g.stylesheets     false
-  g.javascripts     false
   g.helper          :my_helper
 end
 ```
@@ -350,7 +348,6 @@ config.generators do |g|
   g.template_engine :erb
   g.test_framework  :test_unit, fixture: false
   g.stylesheets     false
-  g.javascripts     false
 end
 ```
 
@@ -385,7 +382,6 @@ config.generators do |g|
   g.template_engine :erb
   g.test_framework  :shoulda, fixture: false
   g.stylesheets     false
-  g.javascripts     false
 
   # Add a fallback!
   g.fallbacks[:shoulda] = :test_unit
diff --git a/guides/source/i18n.md b/guides/source/i18n.md
index 78e5f27448..c61b6ad214 100644
--- a/guides/source/i18n.md
+++ b/guides/source/i18n.md
@@ -116,7 +116,7 @@ NOTE: The backend lazy-loads these translations when a translation is looked up
 You can change the default locale as well as configure the translations load paths in `config/application.rb` as follows:
 
 ```ruby
-  config.i18n.load_path += Dir[Rails.root.join('my', 'locales', '*.{rb,yml}').to_s]
+  config.i18n.load_path += Dir[Rails.root.join('my', 'locales', '*.{rb,yml}')]
   config.i18n.default_locale = :de
 ```
 
@@ -135,6 +135,8 @@ I18n.available_locales = [:en, :pt]
 I18n.default_locale = :pt
 ```
 
+Note that appending directly to `I18n.load_paths` instead of to the application's configured i18n will _not_ override translations from external gems.
+
 ### Managing the Locale across Requests
 
 The default locale is used for all translations unless `I18n.locale` is explicitly set.
@@ -662,6 +664,26 @@ I18n.t 'activerecord.errors.messages'
 # => {:inclusion=>"is not included in the list", :exclusion=> ... }
 ```
 
+If you want to perform interpolation on a bulk hash of translations, you need to pass `deep_interpolation: true` as a parameter. When you have the following dictionary:
+
+```yaml
+en:
+  welcome:
+    title: "Welcome!"
+    content: "Welcome to the %{app_name}"
+```
+
+then the nested interpolation will be ignored without the setting:
+
+```ruby
+I18n.t 'welcome', app_name: 'book store'
+# => {:title=>"Welcome!", :content=>"Welcome to the %{app_name}"}
+
+I18n.t 'welcome', deep_interpolation: true, app_name: 'book store'
+# => {:title=>"Welcome!", :content=>"Welcome to the book store"}
+```
+
+
 #### "Lazy" Lookup
 
 Rails implements a convenient way to look up the locale inside _views_. When you have the following dictionary:
@@ -1103,7 +1125,7 @@ For several reasons the Simple backend shipped with Active Support only does the
 
 That does not mean you're stuck with these limitations, though. The Ruby I18n gem makes it very easy to exchange the Simple backend implementation with something else that fits better for your needs, by passing a backend instance to the `I18n.backend=` setter.
 
-For example, you can replace the Simple backend with the the Chain backend to chain multiple backends together. This is useful when you want to use standard translations with a Simple backend but store custom application translations in a database or other backends.
+For example, you can replace the Simple backend with the Chain backend to chain multiple backends together. This is useful when you want to use standard translations with a Simple backend but store custom application translations in a database or other backends.
 
 With the Chain backend, you could use the Active Record backend and fall back to the (default) Simple backend:
 
diff --git a/guides/source/layout.html.erb b/guides/source/layout.html.erb
index dd9175e312..1f42d72756 100644
--- a/guides/source/layout.html.erb
+++ b/guides/source/layout.html.erb
@@ -45,16 +45,16 @@
           <a href="index.html" id="guidesMenu" class="guides-index-item nav-item">Guides Index</a>
           <div id="guides" class="clearfix" style="display: none;">
             <hr />
-            <% ['L', 'R'].each do |position| %>
-              <dl class="<%= position %>">
-              <% docs_for_menu(position).each do |section| %>
-                <dt><%= section['name'] %></dt>
-                <% finished_documents(section['documents']).each do |document| %>
-                <dd><a href="<%= document['url'] %>"><%= document['name'] %></a></dd>
-                <% end %>
+            <div class="guides-section-container">
+              <% documents_by_section.each do |section| %>
+                <div class="guides-section">
+                  <dt><%= section['name'] %></dt>
+                  <% finished_documents(section['documents']).each do |document| %>
+                  <dd><a href="<%= document['url'] %>"><%= document['name'] %></a></dd>
+                  <% end %>
+                </div>
               <% end %>
-              </dl>
-            <% end %>
+            </div>
           </div>
         </li>
         <li><a class="nav-item" href="contributing_to_ruby_on_rails.html">Contribute</a></li>
diff --git a/guides/source/layouts_and_rendering.md b/guides/source/layouts_and_rendering.md
index 00da65b784..ad08e5a5a9 100644
--- a/guides/source/layouts_and_rendering.md
+++ b/guides/source/layouts_and_rendering.md
@@ -1266,7 +1266,7 @@ You can also pass in arbitrary local variables to any partial you are rendering
 
 In this case, the partial will have access to a local variable `title` with the value "Products Page".
 
-TIP: Rails also makes a counter variable available within a partial called by the collection, named after the title of the partial followed by `_counter`. For example, when rendering a collection `@products` the partial `_product.html.erb` can access the variable `product_counter` which indexes the number of times it has been rendered within the enclosing view.
+TIP: Rails also makes a counter variable available within a partial called by the collection, named after the title of the partial followed by `_counter`. For example, when rendering a collection `@products` the partial `_product.html.erb` can access the variable `product_counter` which indexes the number of times it has been rendered within the enclosing view. Note that it also applies for when the partial name was changed by using the `as:` option. For example, the counter variable for the code above would be `item_counter`.
 
 You can also specify a second partial to be rendered between instances of the main partial by using the `:spacer_template` option:
 
diff --git a/guides/source/testing.md b/guides/source/testing.md
index 9de2229672..8c21ccfba6 100644
--- a/guides/source/testing.md
+++ b/guides/source/testing.md
@@ -1562,7 +1562,7 @@ class UserMailerTest < ActionMailer::TestCase
 end
 ```
 
-In the test we send the email and store the returned object in the `email`
+In the test we create the email and store the returned object in the `email`
 variable. We then ensure that it was sent (the first assert), then, in the
 second batch of assertions, we ensure that the email does indeed contain what we
 expect. The helper `read_fixture` is used to read in the content from this file.