Change the request.env example in AC::Base docs to a var that exists...

Change the request.env example in AC::Base docs to a var that exists (REMOTE_IP doesn't) and isn't already wrapped by a request method (i.e. request.remote_ip).  Closes #5113.

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@4347 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

actionpack/lib/action_controller/base.rb

@@ -87,9 +87,9 @@ def initialize(message = nil)
   # The full request object is available with the request accessor and is primarily used to query for http headers. These queries
   # are made by accessing the environment hash, like this:
   #
-  #   def hello_ip
-  #     location = request.env["REMOTE_IP"]
-  #     render :text => "Hello stranger from #{location}"
+  #   def server_ip
+  #     location = request.env["SERVER_ADDR"]
+  #     render :text => "This server hosted at #{location}"
   #   end
   #
   # == Parameters