Updated screenshots.

git-svn-id: https://plugins.svn.wordpress.org/customize-wpadmin/trunk@1020263 b8457f37-d9ea-0310-8a92-e5e31aec5664
Updated screenshot captions.

git-svn-id: https://plugins.svn.wordpress.org/customize-wpadmin/trunk@1020267 b8457f37-d9ea-0310-8a92-e5e31aec5664