update readme to 3.8

git-svn-id: https://plugins.svn.wordpress.org/links-with-icons-widget/trunk@818642 b8457f37-d9ea-0310-8a92-e5e31aec5664
update readme to 3.8

git-svn-id: https://plugins.svn.wordpress.org/links-with-icons-widget/trunk@818643 b8457f37-d9ea-0310-8a92-e5e31aec5664