1 files changed, 19 insertions, 32 deletions
diff --git a/guides/source/action_controller_overview.md b/guides/source/action_controller_overview.md
index 5d987264f5..6ecfb57db3 100644
--- a/guides/source/action_controller_overview.md
+++ b/guides/source/action_controller_overview.md
@@ -21,9 +21,9 @@ After reading this guide, you will know:
 What Does a Controller Do?
 --------------------------
 
-Action Controller is the C in MVC. After the router has determined which controller to use for a request, the controller is responsible for making sense of the request and producing the appropriate output. Luckily, Action Controller does most of the groundwork for you and uses smart conventions to make this as straightforward as possible.
+Action Controller is the C in [MVC](https://en.wikipedia.org/wiki/Model%E2%80%93view%E2%80%93controller). After the router has determined which controller to use for a request, the controller is responsible for making sense of the request, and producing the appropriate output. Luckily, Action Controller does most of the groundwork for you and uses smart conventions to make this as straightforward as possible.
 
-For most conventional [RESTful](http://en.wikipedia.org/wiki/Representational_state_transfer) applications, the controller will receive the request (this is invisible to you as the developer), fetch or save data from a model and use a view to create HTML output. If your controller needs to do things a little differently, that's not a problem, this is just the most common way for a controller to work.
+For most conventional [RESTful](https://en.wikipedia.org/wiki/Representational_state_transfer) applications, the controller will receive the request (this is invisible to you as the developer), fetch or save data from a model and use a view to create HTML output. If your controller needs to do things a little differently, that's not a problem, this is just the most common way for a controller to work.
 
 A controller can thus be thought of as a middleman between models and views. It makes the model data available to the view so it can display that data to the user, and it saves or updates user data to the model.
 
@@ -397,34 +397,18 @@ You can also pass a `:domain` key and specify the domain name for the cookie:
 Rails.application.config.session_store :cookie_store, key: '_your_app_session', domain: ".example.com"
 ```
 
-Rails sets up (for the CookieStore) a secret key used for signing the session data. This can be changed in `config/secrets.yml`
+Rails sets up (for the CookieStore) a secret key used for signing the session data in `config/credentials.yml.enc`. This can be changed with `bin/rails credentials:edit`.
 
 ```ruby
-# Be sure to restart your server when you modify this file.
-
-# Your secret key is used for verifying the integrity of signed cookies.
-# If you change this key, all old signed cookies will become invalid!
-
-# Make sure the secret is at least 30 characters and all random,
-# no regular words or you'll be exposed to dictionary attacks.
-# You can use `rails secret` to generate a secure secret key.
-
-# Make sure the secrets in this file are kept private
-# if you're sharing your code publicly.
+# aws:
+#   access_key_id: 123
+#   secret_access_key: 345
 
-development:
-  secret_key_base: a75d...
-
-test:
-  secret_key_base: 492f...
-
-# Do not keep production secrets in the repository,
-# instead read values from the environment.
-production:
-  secret_key_base: <%= ENV["SECRET_KEY_BASE"] %>
+# Used as the base secret for all MessageVerifiers in Rails, including the one protecting cookies.
+secret_key_base: 492f...
 ```
 
-NOTE: Changing the secret when using the `CookieStore` will invalidate all existing sessions.
+NOTE: Changing the secret_key_base when using the `CookieStore` will invalidate all existing sessions.
 
 ### Accessing the Session
 
@@ -670,8 +654,8 @@ class UsersController < ApplicationController
     @users = User.all
     respond_to do |format|
       format.html # index.html.erb
-      format.xml  { render xml: @users}
-      format.json { render json: @users}
+      format.xml  { render xml: @users }
+      format.json { render json: @users }
     end
   end
 end
@@ -715,6 +699,9 @@ end
 
 Now, the `LoginsController`'s `new` and `create` actions will work as before without requiring the user to be logged in. The `:only` option is used to skip this filter only for these actions, and there is also an `:except` option which works the other way. These options can be used when adding filters too, so you can add a filter which only runs for selected actions in the first place.
 
+NOTE: Calling the same filter multiple times with different options will not work,
+since the last filter definition will overwrite the previous ones.
+
 ### After Filters and Around Filters
 
 In addition to "before" filters, you can also run filters after an action has been executed, or both before and after.
@@ -797,9 +784,9 @@ The way this is done is to add a non-guessable token which is only known to your
 If you generate a form like this:
 
 ```erb
-<%= form_for @user do |f| %>
-  <%= f.text_field :username %>
-  <%= f.text_field :password %>
+<%= form_with model: @user, local: true do |form| %>
+  <%= form.text_field :username %>
+  <%= form.text_field :password %>
 <% end %>
 ```
 
@@ -1129,7 +1116,7 @@ Rails default exception handling displays a "500 Server Error" message for all e
 
 ### The Default 500 and 404 Templates
 
-By default a production application will render either a 404 or a 500 error message, in the development environment all unhandled exceptions are raised. These messages are contained in static HTML files in the `public` folder, in `404.html` and `500.html` respectively. You can customize these files to add some extra information and style, but remember that they are static HTML; i.e. you can't use ERB, SCSS, CoffeeScript, or layouts for them.
+By default a production application will render either a 404 or a 500 error message, in the development environment all unhandled exceptions are raised. These messages are contained in static HTML files in the public folder, in `404.html` and `500.html` respectively. You can customize these files to add some extra information and style, but remember that they are static HTML; i.e. you can't use ERB, SCSS, CoffeeScript, or layouts for them.
 
 ### `rescue_from`
 
@@ -1183,7 +1170,7 @@ class ClientsController < ApplicationController
 end
 ```
 
-WARNING: You shouldn't do `rescue_from Exception` or `rescue_from StandardError` unless you have a particular reason as it will cause serious side-effects (e.g. you won't be able to see exception details and tracebacks during development).
+WARNING: Using `rescue_from` with `Exception` or `StandardError` would cause serious side-effects as it prevents Rails from handling exceptions properly. As such, it is not recommended to do so unless there is a strong reason.
 
 NOTE: When running in the production environment, all
 `ActiveRecord::RecordNotFound` errors render the 404 error page. Unless you need