Merge pull request #16930 from todd/upgrade_guide

Added Responders docs, made Web Console docs more consistent. [ci skip]

guides/source/upgrading_ruby_on_rails.md

@@ -55,15 +55,51 @@ a [pull request](https://github.com/rails/rails/edit/master/guides/source/upgrad
 
 ### Web Console
 
-First, add `gem 'web-console', '~> 2.0.0.beta3'` to the `:development` group in your Gemfile and run `bundle install` (it won't have been included when you upgraded Rails). Once it's been installed, you can simply drop a reference to the console helper (i.e., `<%= console %>`) into any view you want to enable it for. A console will also be provided on any error page you view in your development environment.
+First, add `gem 'web-console', '~> 2.0'` to the `:development` group in your Gemfile and run `bundle install` (it won't have been included when you upgraded Rails). Once it's been installed, you can simply drop a reference to the console helper (i.e., `<%= console %>`) into any view you want to enable it for. A console will also be provided on any error page you view in your development environment.
 
-Additionally, you can tell Rails to automatically mount a VT100-compatible console on a predetermined path by setting `config.web_console.automount = true` in your `config/environments/development.rb`. You can specify the path by setting `config.web_console.default_mount_path` (note that this defaults to `/console`).
+Additionally, you can tell Rails to automatically mount a VT100-compatible console on a predetermined path by setting the appropriate configuration flags in your development config:
 
-TODO: Update `web-console` version to release version.
+```ruby
+# config/environments/development.rb
+
+config.web_console.automount = true
+config.web_console.default_mount_path = '/terminal' # Optional, defaults to /console
+```
 
 ### Responders
 
-TODO: mention https://github.com/rails/rails/pull/16526
+`respond_with` and the class-level `respond_to` methods have been extracted to the `responders` gem. To use them, simply add `gem 'responders', '~> 2.0'` to your Gemfile. Calls to `respond_with` and `respond_to` (again, at the class level) will no longer work without having included the `responders` gem in your dependencies:
+
+```ruby
+# app/controllers/users_controller.rb
+
+class UsersController < ApplicationController
+  respond_to :html, :json
+
+  def show
+    @user = User.find(params[:id])
+    respond_with @user
+  end
+end
+```
+
+Instance-level `respond_to` is unaffected and does not require the additional gem:
+
+```ruby
+# app/controllers/users_controller.rb
+
+class UsersController < ApplicationController
+  def show
+    @user = User.find(params[:id])
+    respond_to do |format|
+      format.html
+      format.json { render json: @user }
+    end
+  end
+end
+```
+
+See [#16526](https://github.com/rails/rails/pull/16526) for more details.
 
 ### Error handling in transaction callbacks