update readme file

git-svn-id: https://plugins.svn.wordpress.org/groupdocs-comparison/trunk@802952 b8457f37-d9ea-0310-8a92-e5e31aec5664
updated readme file

git-svn-id: https://plugins.svn.wordpress.org/groupdocs-comparison/trunk@804738 b8457f37-d9ea-0310-8a92-e5e31aec5664