updated referral to point to the new ads-campaigns plugin

git-svn-id: https://plugins.svn.wordpress.org/wishpond-social-campaigns/trunk@883852 b8457f37-d9ea-0310-8a92-e5e31aec5664
updated link of ads-campaigns plugin in description

git-svn-id: https://plugins.svn.wordpress.org/wishpond-social-campaigns/trunk@883854 b8457f37-d9ea-0310-8a92-e5e31aec5664