Fixed #3325: Added docs/distributions.txt, a guide to packaged versions of Django in Debian/Fedora/etc.  Thanks to Marc Fargas and Ubernostrum for the patches.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@4629 bcc190cf-cafb-0310-a4f2-bffc1f526a37