edit readme.txt

git-svn-id: https://plugins.svn.wordpress.org/like-box/trunk@1031881 b8457f37-d9ea-0310-8a92-e5e31aec5664
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git-svn-id: https://plugins.svn.wordpress.org/like-box/trunk@1031884 b8457f37-d9ea-0310-8a92-e5e31aec5664