added note to readme about crawling dashboards

git-svn-id: https://plugins.svn.wordpress.org/conditional-widgets/trunk@987302 b8457f37-d9ea-0310-8a92-e5e31aec5664
tested up to 4.0

git-svn-id: https://plugins.svn.wordpress.org/conditional-widgets/trunk@987304 b8457f37-d9ea-0310-8a92-e5e31aec5664