update readme

git-svn-id: https://plugins.svn.wordpress.org/kakao-talk-link/trunk@1011107 b8457f37-d9ea-0310-8a92-e5e31aec5664
update plugin info

git-svn-id: https://plugins.svn.wordpress.org/kakao-talk-link/trunk@1011109 b8457f37-d9ea-0310-8a92-e5e31aec5664