in feedback solicitation text, correct that docrails is fork, not branch

guides/source/layout.html.erb

@@ -82,7 +82,7 @@
         <p>
           If you see any typos or factual errors you are confident to
           patch, please clone <%= link_to 'docrails', 'https://github.com/lifo/docrails' %>
-          and push the change yourself. That branch of Rails has public write access.
+          and push the change yourself. That fork of Rails has public write access.
           Commits are still reviewed, but that happens after you've submitted your
           contribution. <%= link_to 'docrails', 'https://github.com/lifo/docrails' %> is
           cross-merged with master periodically.