changing README.txt

git-svn-id: https://plugins.svn.wordpress.org/ns-shortcodes/trunk@836017 b8457f37-d9ea-0310-8a92-e5e31aec5664
aru change

git-svn-id: https://plugins.svn.wordpress.org/ns-shortcodes/trunk@836019 b8457f37-d9ea-0310-8a92-e5e31aec5664