clarify that documentation bugs have to be reported as Rails issues. [Closes #2858]

railties/guides/source/layout.html.erb

@@ -129,6 +129,10 @@
           <%= link_to 'Ruby on Rails Guides Guidelines', 'ruby_on_rails_guides_guidelines.html' %>
           for style and conventions.
         </p>
+        <p>
+          If for whatever reason you spot something to fix but cannot patch it yourself, please
+          <%= link_to 'open an issue', 'https://github.com/rails/rails/issues' %>.
+        </p>
         <p>And last but not least, any kind of discussion regarding Ruby on Rails
           documentation is very welcome in the <%= link_to 'rubyonrails-docs mailing list', 'http://groups.google.com/group/rubyonrails-docs' %>.
         </p>