update screenshot desc

git-svn-id: https://plugins.svn.wordpress.org/wp-frontpage-news/trunk@992082 b8457f37-d9ea-0310-8a92-e5e31aec5664
update screen description

git-svn-id: https://plugins.svn.wordpress.org/wp-frontpage-news/trunk@992083 b8457f37-d9ea-0310-8a92-e5e31aec5664