[1.1.X] Fixed #11359 -- Added a link to the signals topic guide in the signals...

[1.1.X] Fixed #11359 -- Added a link to the signals topic guide in the signals reference. Thanks to tyson for the suggestion.

Merge of r11540 and r11554 from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.1.X@11562 bcc190cf-cafb-0310-a4f2-bffc1f526a37