Update readme for 3.9

git-svn-id: https://plugins.svn.wordpress.org/change-permalink-helper/trunk@895788 b8457f37-d9ea-0310-8a92-e5e31aec5664
Fix link

git-svn-id: https://plugins.svn.wordpress.org/change-permalink-helper/trunk@895789 b8457f37-d9ea-0310-8a92-e5e31aec5664