Updated readme

git-svn-id: https://plugins.svn.wordpress.org/wordpress-seo/trunk@963373 b8457f37-d9ea-0310-8a92-e5e31aec5664
Updated readme

git-svn-id: https://plugins.svn.wordpress.org/wordpress-seo/trunk@963375 b8457f37-d9ea-0310-8a92-e5e31aec5664