update readme.txt

git-svn-id: https://plugins.svn.wordpress.org/noindex-links/trunk@999020 b8457f37-d9ea-0310-8a92-e5e31aec5664
update readme.txt

git-svn-id: https://plugins.svn.wordpress.org/noindex-links/trunk@999022 b8457f37-d9ea-0310-8a92-e5e31aec5664
update readme.txt

git-svn-id: https://plugins.svn.wordpress.org/noindex-links/trunk@999025 b8457f37-d9ea-0310-8a92-e5e31aec5664