Update readme. Add mini tour. Update global nav plugin page only

git-svn-id: https://plugins.svn.wordpress.org/newsme/trunk@968170 b8457f37-d9ea-0310-8a92-e5e31aec5664
Remove extra space in readme

git-svn-id: https://plugins.svn.wordpress.org/newsme/trunk@968177 b8457f37-d9ea-0310-8a92-e5e31aec5664