6 files changed, 77 insertions, 5 deletions
diff --git a/guides/source/association_basics.md b/guides/source/association_basics.md
index dab885a8fb..8633cc4f10 100644
--- a/guides/source/association_basics.md
+++ b/guides/source/association_basics.md
@@ -2243,3 +2243,67 @@ Extensions can refer to the internals of the association proxy using these three
 * `proxy_association.owner` returns the object that the association is a part of.
 * `proxy_association.reflection` returns the reflection object that describes the association.
 * `proxy_association.target` returns the associated object for `belongs_to` or `has_one`, or the collection of associated objects for `has_many` or `has_and_belongs_to_many`.
+
+Single Table Inheritance
+------------------------
+
+Sometimes, you may want to share fields and behavior between different models.
+Let's say we have Car, Motorcycle and Bicycle models. We will want to share
+the `color` and `price` fields and some methods for all of them, but having some
+specific behavior for each, and separated controllers too.
+
+Rails makes this quite easy. First, let's generate the base Vehicle model:
+
+```bash
+$ rails generate model vehicle type:string color:string price:decimal{10.2}
+```
+
+Did you note we are adding a "type" field? Since all models will be saved in a
+single database table, Rails will save in this column the name of the model that
+is being saved. In our example, this can be "Car", "Motorcycle" or "Bicycle."
+STI won't work without a "type" field in the table.
+
+Next, we will generate the three models that inherit from Vehicle. For this,
+we can use the `--parent=PARENT` option, which will generate a model that
+inherits from the specified parent and without equivalent migration (since the
+table already exists).
+
+For example, to generate the Car model:
+
+```bash
+$ rails generate model car --parent=Vehicle
+```
+
+The generated model will look like this:
+
+```ruby
+class Car < Vehicle
+end
+```
+
+This means that all behavior added to Vehicle is available for Car too, as
+associations, public methods, etc.
+
+Creating a car will save it in the `vehicles` table with "Car" as the `type` field:
+
+```ruby
+Car.create color: 'Red', price: 10000
+```
+
+will generate the following SQL:
+
+```sql
+INSERT INTO "vehicles" ("type", "color", "price") VALUES ("Car", "Red", 10000)
+```
+
+Querying car records will just search for vehicles that are cars:
+
+```ruby
+Car.all
+```
+
+will run a query like:
+
+```sql
+SELECT "vehicles".* FROM "vehicles" WHERE "vehicles"."type" IN ('Car')
+```
diff --git a/guides/source/autoloading_and_reloading_constants.md b/guides/source/autoloading_and_reloading_constants.md
index f0ef03f0ce..8f9125f311 100644
--- a/guides/source/autoloading_and_reloading_constants.md
+++ b/guides/source/autoloading_and_reloading_constants.md
@@ -461,8 +461,9 @@ Also, this collection is configurable via `config.autoload_paths`. For example,
 by adding this to `config/application.rb`:
 
 ```ruby
-config.autoload_paths += "#{Rails.root}/lib"
+config.autoload_paths << "#{Rails.root}/lib"
 ```
+`config.autoload_paths` is accessible from environment-specific configuration files, but any changes made to it outside `config/application.rb` don't have an effect.
 
 The value of `autoload_paths` can be inspected. In a just generated application
 it is (edited):
diff --git a/guides/source/debugging_rails_applications.md b/guides/source/debugging_rails_applications.md
index a788dd48ad..f6e7980fe2 100644
--- a/guides/source/debugging_rails_applications.md
+++ b/guides/source/debugging_rails_applications.md
@@ -544,7 +544,7 @@ This way an irb session will be started within the context you invoked it. But
 be warned: this is an experimental feature.
 
 The `var` method is the most convenient way to show variables and their values.
-Let's let `byebug` to help us with it.
+Let's let `byebug` help us with it.
 
 ```
 (byebug) help var
diff --git a/guides/source/form_helpers.md b/guides/source/form_helpers.md
index 4c02c99cc7..90004c611b 100644
--- a/guides/source/form_helpers.md
+++ b/guides/source/form_helpers.md
@@ -687,7 +687,14 @@ class LabellingFormBuilder < ActionView::Helpers::FormBuilder
 end
 ```
 
-If you reuse this frequently you could define a `labeled_form_for` helper that automatically applies the `builder: LabellingFormBuilder` option.
+If you reuse this frequently you could define a `labeled_form_for` helper that automatically applies the `builder: LabellingFormBuilder` option:
+
+```ruby
+def labeled_form_for(record, options = {}, &block)
+  options.merge! builder: LabellingFormBuilder
+  form_for record, options, &block
+end
+```
 
 The form builder used also determines what happens when you do
 
diff --git a/guides/source/upgrading_ruby_on_rails.md b/guides/source/upgrading_ruby_on_rails.md
index d7fbe575c2..909a92b9dd 100644
--- a/guides/source/upgrading_ruby_on_rails.md
+++ b/guides/source/upgrading_ruby_on_rails.md
@@ -534,7 +534,7 @@ module FixtureFileHelpers
     Digest::SHA2.hexdigest(File.read(Rails.root.join('test/fixtures', path)))
   end
 end
-ActiveRecord::FixtureSet.context_class.send :include, FixtureFileHelpers
+ActiveRecord::FixtureSet.context_class.include FixtureFileHelpers
 ```
 
 ### I18n enforcing available locales
diff --git a/guides/source/working_with_javascript_in_rails.md b/guides/source/working_with_javascript_in_rails.md
index 367abddcfa..f3d3a83afc 100644
--- a/guides/source/working_with_javascript_in_rails.md
+++ b/guides/source/working_with_javascript_in_rails.md
@@ -357,7 +357,7 @@ This gem uses Ajax to speed up page rendering in most applications.
 
 Turbolinks attaches a click handler to all `<a>` on the page. If your browser
 supports
-[PushState](https://developer.mozilla.org/en-US/docs/DOM/Manipulating_the_browser_history#The_pushState(\).C2.A0method),
+[PushState](https://developer.mozilla.org/en-US/docs/Web/Guide/API/DOM/Manipulating_the_browser_history#The_pushState()_method),
 Turbolinks will make an Ajax request for the page, parse the response, and
 replace the entire `<body>` of the page with the `<body>` of the response. It
 will then use PushState to change the URL to the correct one, preserving