adjusting readme description

git-svn-id: https://plugins.svn.wordpress.org/thirstyaffiliates/trunk@764112 b8457f37-d9ea-0310-8a92-e5e31aec5664
adjusting readme description

git-svn-id: https://plugins.svn.wordpress.org/thirstyaffiliates/trunk@764113 b8457f37-d9ea-0310-8a92-e5e31aec5664