no markdown in readme for screenshot

git-svn-id: https://plugins.svn.wordpress.org/responsive-widgets/trunk@873134 b8457f37-d9ea-0310-8a92-e5e31aec5664
Since the readme example wasn't correct lets try adding screenshots this way.

git-svn-id: https://plugins.svn.wordpress.org/responsive-widgets/trunk@873136 b8457f37-d9ea-0310-8a92-e5e31aec5664
Another screenshot attempt

git-svn-id: https://plugins.svn.wordpress.org/responsive-widgets/trunk@873139 b8457f37-d9ea-0310-8a92-e5e31aec5664