Added features in readme.txt

git-svn-id: https://plugins.svn.wordpress.org/site-locator-map-free/trunk@1003561 b8457f37-d9ea-0310-8a92-e5e31aec5664
added description

git-svn-id: https://plugins.svn.wordpress.org/site-locator-map-free/trunk@1003562 b8457f37-d9ea-0310-8a92-e5e31aec5664