Fixed #9967 - Added a link to a bug that affects contrib.comments redirects.

docs/ref/contrib/comments/index.txt

@@ -158,11 +158,13 @@ For example::
 
 .. warning::
 
-    There's a known bug in Safari/Webkit which causes the named anchor to be
+    There's a `known bug`_ in Safari/Webkit which causes the named anchor to be
     forgotten following a redirect. The practical impact for comments is that
     the Safari/webkit browsers will arrive at the correct page but will not
     scroll to the named anchor.
 
+.. _`known bug`: https://bugs.webkit.org/show_bug.cgi?id=24175
+
 .. templatetag:: get_comment_count
 
 Counting comments