readme update

git-svn-id: https://plugins.svn.wordpress.org/wpsso/trunk@853371 b8457f37-d9ea-0310-8a92-e5e31aec5664
2.1dev1

git-svn-id: https://plugins.svn.wordpress.org/wpsso/trunk@853373 b8457f37-d9ea-0310-8a92-e5e31aec5664