fix a comment in atom_feed_helper.rb

actionview/lib/action_view/helpers/atom_feed_helper.rb

@@ -132,7 +132,7 @@ def initialize(xml)
         end
 
         private
-          # Delegate to xml builder, first wrapping the element in a xhtml
+          # Delegate to xml builder, first wrapping the element in an xhtml
           # namespaced div element if the method and arguments indicate
           # that an xhtml_block? is desired.
           def method_missing(method, *arguments, &block)