[1.1.X] Fixed #13336 -- Corrected an incorrect example of cache header usage....

[1.1.X] Fixed #13336 -- Corrected an incorrect example of cache header usage. Thanks to dnjuls for the report, and claudep for the patch.

Backport of r13129 from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.1.X@13132 bcc190cf-cafb-0310-a4f2-bffc1f526a37