updated readme.txt

git-svn-id: https://plugins.svn.wordpress.org/dewdrop-custom-scrollbar/trunk@944837 b8457f37-d9ea-0310-8a92-e5e31aec5664
updated readme.txt

git-svn-id: https://plugins.svn.wordpress.org/dewdrop-custom-scrollbar/trunk@944838 b8457f37-d9ea-0310-8a92-e5e31aec5664