Negligible change to docs/topics/cache.txt so I can test something in the docs on the live site

git-svn-id: http://code.djangoproject.com/svn/django/trunk@12135 bcc190cf-cafb-0310-a4f2-bffc1f526a37

docs/topics/cache.txt

@@ -754,7 +754,7 @@ Other optimizations
 ===================
 
 Django comes with a few other pieces of middleware that can help optimize your
-apps' performance:
+site's performance:
 
     * ``django.middleware.http.ConditionalGetMiddleware`` adds support for
       modern browsers to conditionally GET responses based on the ``ETag``