Document the :xhr option for verifications. Closes #3666.

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@3507 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

actionpack/CHANGELOG

 *SVN*
 
+* Document the :xhr option for verifications. #3666 [leeo]
+
 * Added :only and :except controls to skip_before/after_filter just like for when you add filters [DHH]
 
 * Ensure that the instance variables are copied to the template when performing render :update. [Nicholas Seckar]

actionpack/lib/action_controller/verification.rb

@@ -47,6 +47,8 @@ module ClassMethods
       #   must match the current request method in order for the action(s) to
       #   be safely called. (The key should be a symbol: <tt>:get</tt> or
       #   <tt>:post</tt>, for example.)
+      # * <tt>:xhr</tt>: true/false option to ensure that the request is coming
+      #   from an Ajax call or not. 
       # * <tt>:add_flash</tt>: a hash of name/value pairs that should be merged
       #   into the session's flash if the prerequisites cannot be satisfied.
       # * <tt>:redirect_to</tt>: the redirection parameters to be used when