remove unnecessary use of 'Example'

railties/guides/source/rails_on_rack.textile

@@ -117,8 +117,6 @@ You can add a new middleware to the middleware stack using any of the following
 
 * +config.middleware.insert_after(existing_middleware, new_middleware, args)+ - Adds the new middleware after the specified existing middleware in the middleware stack.
 
-<strong>Example:</strong>
-
 <ruby>
 # config/environment.rb
 
@@ -134,8 +132,6 @@ h5. Swapping a Middleware
 
 You can swap an existing middleware in the middleware stack using +config.middleware.swap+.
 
-<strong>Example:</strong>
-
 <ruby>
 # config/environment.rb
 
@@ -173,8 +169,6 @@ h4. Customizing Internal Middleware Stack
 
 It's possible to replace the entire middleware stack with a custom stack using +ActionController::Dispatcher.middleware=+.
 
-<strong>Example:</strong>
-
 Put the following in an initializer:
 
 <ruby>