Updated readme.txt

git-svn-id: https://plugins.svn.wordpress.org/multi-rating/trunk@1031572 b8457f37-d9ea-0310-8a92-e5e31aec5664
Updated the about page to list the ratings moderation functionality in Pro version

git-svn-id: https://plugins.svn.wordpress.org/multi-rating/trunk@1031574 b8457f37-d9ea-0310-8a92-e5e31aec5664