update readme

git-svn-id: https://plugins.svn.wordpress.org/cm-ad-changer/trunk@903766 b8457f37-d9ea-0310-8a92-e5e31aec5664
update readme

git-svn-id: https://plugins.svn.wordpress.org/cm-ad-changer/trunk@903767 b8457f37-d9ea-0310-8a92-e5e31aec5664
update readme

git-svn-id: https://plugins.svn.wordpress.org/cm-ad-changer/trunk@903768 b8457f37-d9ea-0310-8a92-e5e31aec5664