[1.2.X] Fixed #14141: docs now use the :doc: construct for links between documents.

Thanks, Ramiro Morales.

Backport of [13608] from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.2.X@13609 bcc190cf-cafb-0310-a4f2-bffc1f526a37