Fixed #14676 - Document that the removetags filter is case-sensitive. Thanks...

Fixed #14676 - Document that the removetags filter is case-sensitive. Thanks peterh32 for the report and elbarto for the patch.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@14925 bcc190cf-cafb-0310-a4f2-bffc1f526a37