updated readme with screenshots

git-svn-id: https://plugins.svn.wordpress.org/cat-game/trunk@970265 b8457f37-d9ea-0310-8a92-e5e31aec5664
renamed screenshots

git-svn-id: https://plugins.svn.wordpress.org/cat-game/trunk@970272 b8457f37-d9ea-0310-8a92-e5e31aec5664
added screenshots to svn

git-svn-id: https://plugins.svn.wordpress.org/cat-game/trunk@970277 b8457f37-d9ea-0310-8a92-e5e31aec5664