Replace ActionDispatch::Head with Rack::Head.

guides/source/configuring.md

@@ -214,7 +214,7 @@ Every Rails application comes with a standard set of middleware which it uses in
 * `ActionDispatch::Flash` sets up the `flash` keys. Only available if `config.action_controller.session_store` is set to a value.
 * `ActionDispatch::ParamsParser` parses out parameters from the request into `params`.
 * `Rack::MethodOverride` allows the method to be overridden if `params[:_method]` is set. This is the middleware which supports the PATCH, PUT, and DELETE HTTP method types.
-* `ActionDispatch::Head` converts HEAD requests to GET requests and serves them as so.
+* `Rack::Head` converts HEAD requests to GET requests and serves them as so.
 
 Besides these usual middleware, you can add your own by using the `config.middleware.use` method:
 
@@ -225,13 +225,13 @@ config.middleware.use Magical::Unicorns
 This will put the `Magical::Unicorns` middleware on the end of the stack. You can use `insert_before` if you wish to add a middleware before another.
 
 ```ruby
-config.middleware.insert_before ActionDispatch::Head, Magical::Unicorns
+config.middleware.insert_before Rack::Head, Magical::Unicorns
 ```
 
 There's also `insert_after` which will insert a middleware after another:
 
 ```ruby
-config.middleware.insert_after ActionDispatch::Head, Magical::Unicorns
+config.middleware.insert_after Rack::Head, Magical::Unicorns
 ```
 
 Middlewares can also be completely swapped out and replaced with others:

railties/lib/rails/configuration.rb

@@ -18,11 +18,11 @@ module Configuration
     # This will put the <tt>Magical::Unicorns</tt> middleware on the end of the stack.
     # You can use +insert_before+ if you wish to add a middleware before another:
     #
-    #     config.middleware.insert_before ActionDispatch::Head, Magical::Unicorns
+    #     config.middleware.insert_before Rack::Head, Magical::Unicorns
     #
     # There's also +insert_after+ which will insert a middleware after another:
     #
-    #     config.middleware.insert_after ActionDispatch::Head, Magical::Unicorns
+    #     config.middleware.insert_after Rack::Head, Magical::Unicorns
     #
     # Middlewares can also be completely swapped out and replaced with others:
     #