updated readme.txt

git-svn-id: https://plugins.svn.wordpress.org/ultimate-social-media-icons/trunk@994763 b8457f37-d9ea-0310-8a92-e5e31aec5664
updated readme.txt

git-svn-id: https://plugins.svn.wordpress.org/ultimate-social-media-icons/trunk@994764 b8457f37-d9ea-0310-8a92-e5e31aec5664