Updated readme with latest compat info

git-svn-id: https://plugins.svn.wordpress.org/authanvil-wordpress-logon-agent/trunk@969264 b8457f37-d9ea-0310-8a92-e5e31aec5664
Updated readme with latest compat info

git-svn-id: https://plugins.svn.wordpress.org/authanvil-wordpress-logon-agent/trunk@969267 b8457f37-d9ea-0310-8a92-e5e31aec5664