updated plugin meta info

git-svn-id: https://plugins.svn.wordpress.org/wp-asset-manager/trunk@893533 b8457f37-d9ea-0310-8a92-e5e31aec5664
Updated support details in README

git-svn-id: https://plugins.svn.wordpress.org/wp-asset-manager/trunk@893534 b8457f37-d9ea-0310-8a92-e5e31aec5664