Update readme file

git-svn-id: https://plugins.svn.wordpress.org/custom-share-buttons-with-floating-sidebar/trunk@1044929 b8457f37-d9ea-0310-8a92-e5e31aec5664
Update readme file

git-svn-id: https://plugins.svn.wordpress.org/custom-share-buttons-with-floating-sidebar/trunk@1044936 b8457f37-d9ea-0310-8a92-e5e31aec5664