Add 'author' to rel attribute for get_the_author_link(). props sirzooro,...

Add 'author' to rel attribute for get_the_author_link(). props sirzooro, CoenJacobs, Ipstenu. fixes #20047.

git-svn-id: https://core.svn.wordpress.org/trunk@20615 1a063a9b-81f0-0310-95a4-ce76da25c4cd