updated readme

git-svn-id: https://plugins.svn.wordpress.org/oasis-workflow/trunk@886593 b8457f37-d9ea-0310-8a92-e5e31aec5664
fixed a typo.

git-svn-id: https://plugins.svn.wordpress.org/oasis-workflow/trunk@886594 b8457f37-d9ea-0310-8a92-e5e31aec5664