Corrected an inconsistency in the documentation regarding the way to specify...

Corrected an inconsistency in the documentation regarding the way to specify the locmem and dummy cache backend. Thanks to Jens Diemer for the report.

r11750 is the backport to 1.1.X of this commit. DVCS Fail.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@11751 bcc190cf-cafb-0310-a4f2-bffc1f526a37