added some links

git-svn-id: https://plugins.svn.wordpress.org/woocommerce-bulk-discount/trunk@817449 b8457f37-d9ea-0310-8a92-e5e31aec5664
added some links

git-svn-id: https://plugins.svn.wordpress.org/woocommerce-bulk-discount/trunk@817451 b8457f37-d9ea-0310-8a92-e5e31aec5664