updated README.txt

git-svn-id: https://plugins.svn.wordpress.org/foogallery/trunk@971294 b8457f37-d9ea-0310-8a92-e5e31aec5664
fixed links

git-svn-id: https://plugins.svn.wordpress.org/foogallery/trunk@971296 b8457f37-d9ea-0310-8a92-e5e31aec5664