Fixed typo in GIS testing docs.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@17541 bcc190cf-cafb-0310-a4f2-bffc1f526a37

docs/ref/contrib/gis/testing.txt

@@ -63,7 +63,7 @@ you may be required to use a database superuser.
 Create database user
 ^^^^^^^^^^^^^^^^^^^^
 
-To make database user with the ability to create databases, use the
+To make a database user with the ability to create databases, use the
 following command::
 
     $ createuser --createdb -R -S <user_name>