update comment in generator.

You'd get an infinite loop with the current one

lib/generators/decorator/templates/decorator.rb

@@ -27,7 +27,7 @@ class <%= class_name %>Decorator < <%= parent_class_name %>
   #   generated by ActiveRecord:
   #
   #   def created_at
-  #     h.content_tag :span, time.strftime("%a %m/%d/%y"),
+  #     h.content_tag :span, attributes["created_at"].strftime("%a %m/%d/%y"),
   #                   :class => 'timestamp'
   #   end
 end