readme updated

git-svn-id: https://plugins.svn.wordpress.org/rocket-responsive-gallery/trunk@861887 b8457f37-d9ea-0310-8a92-e5e31aec5664
readme updated

git-svn-id: https://plugins.svn.wordpress.org/rocket-responsive-gallery/trunk@861958 b8457f37-d9ea-0310-8a92-e5e31aec5664