Screenshots in readme

git-svn-id: https://plugins.svn.wordpress.org/markpress/trunk@960020 b8457f37-d9ea-0310-8a92-e5e31aec5664
Now with the files

git-svn-id: https://plugins.svn.wordpress.org/markpress/trunk@960021 b8457f37-d9ea-0310-8a92-e5e31aec5664