updated readme.txt file for version 1.1

git-svn-id: https://plugins.svn.wordpress.org/easy-mailchimp-opt-in/trunk@984537 b8457f37-d9ea-0310-8a92-e5e31aec5664
Updated mailchimp-optin.php 

git-svn-id: https://plugins.svn.wordpress.org/easy-mailchimp-opt-in/trunk@984538 b8457f37-d9ea-0310-8a92-e5e31aec5664