add readme.txt


git-svn-id: https://plugins.svn.wordpress.org/publishing-stats/trunk@898150 b8457f37-d9ea-0310-8a92-e5e31aec5664
fix version number


git-svn-id: https://plugins.svn.wordpress.org/publishing-stats/trunk@898151 b8457f37-d9ea-0310-8a92-e5e31aec5664