[1.2.X] Fixed #10650 -- Clarified description of MEDIA_ROOT in setting files....

[1.2.X] Fixed #10650 -- Clarified description of MEDIA_ROOT in setting files. Thanks jjconti, tvon, vak, Muhammad Alkarouri and thiggins for their work.

Backport of [14560] from trunk

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.2.X@14561 bcc190cf-cafb-0310-a4f2-bffc1f526a37