[1.2.X] Fixed #14771 -- corrected a typo in the testing docs. Thanks to...

[1.2.X] Fixed #14771 -- corrected a typo in the testing docs.  Thanks to Christian Oudard for the patch. Backport of [14694].

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.2.X@14695 bcc190cf-cafb-0310-a4f2-bffc1f526a37