[1.2.X] Fixed #14789 - remove an unused link from docs/topics/install.txt....

[1.2.X] Fixed #14789 - remove an unused link from docs/topics/install.txt. thanks adamv for the report.

Backport of r14727 from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.2.X@14728 bcc190cf-cafb-0310-a4f2-bffc1f526a37