Fixed #12519 -- Corrected documentation on .raw() queries. Thanks to boralyl...

Fixed #12519 -- Corrected documentation on .raw() queries. Thanks to boralyl for the report and patch.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@12561 bcc190cf-cafb-0310-a4f2-bffc1f526a37