Update to sites.yext.com

git-svn-id: https://plugins.svn.wordpress.org/yext/trunk@814353 b8457f37-d9ea-0310-8a92-e5e31aec5664
update readme

git-svn-id: https://plugins.svn.wordpress.org/yext/trunk@814356 b8457f37-d9ea-0310-8a92-e5e31aec5664