updated readme.txt 1.3

git-svn-id: https://plugins.svn.wordpress.org/easy-mailchimp-opt-in/trunk@985380 b8457f37-d9ea-0310-8a92-e5e31aec5664
1.3 readme.txt

git-svn-id: https://plugins.svn.wordpress.org/easy-mailchimp-opt-in/trunk@985383 b8457f37-d9ea-0310-8a92-e5e31aec5664