update readme.txt

git-svn-id: https://plugins.svn.wordpress.org/custom-preloader/trunk@1042025 b8457f37-d9ea-0310-8a92-e5e31aec5664
update readme.txt

git-svn-id: https://plugins.svn.wordpress.org/custom-preloader/trunk@1042026 b8457f37-d9ea-0310-8a92-e5e31aec5664
update readme.txt

git-svn-id: https://plugins.svn.wordpress.org/custom-preloader/trunk@1042028 b8457f37-d9ea-0310-8a92-e5e31aec5664