[1.2.X] Fixed #12975 -- Moved the docs for contrib.admindocs out of the...

[1.2.X] Fixed #12975 -- Moved the docs for contrib.admindocs out of the template docs and into their own reference section, and significantly improved the documentation of what admindocs can do. Thanks to jabapyth for the report, and whiteinge for the patch.

Backport of [14484] from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.2.X@14485 bcc190cf-cafb-0310-a4f2-bffc1f526a37