update readme file

git-svn-id: https://plugins.svn.wordpress.org/next-event-calendar/trunk@1034997 b8457f37-d9ea-0310-8a92-e5e31aec5664
update readme 2

git-svn-id: https://plugins.svn.wordpress.org/next-event-calendar/trunk@1034998 b8457f37-d9ea-0310-8a92-e5e31aec5664