Move screenshot 1 to assets folder

git-svn-id: https://plugins.svn.wordpress.org/system-requirements-check/trunk@883613 b8457f37-d9ea-0310-8a92-e5e31aec5664
Move screenshot 2 to assets folder

git-svn-id: https://plugins.svn.wordpress.org/system-requirements-check/trunk@883614 b8457f37-d9ea-0310-8a92-e5e31aec5664
Move screenshot 3 to assets folder

git-svn-id: https://plugins.svn.wordpress.org/system-requirements-check/trunk@883615 b8457f37-d9ea-0310-8a92-e5e31aec5664
Move screenshot 3 to assets folder

git-svn-id: https://plugins.svn.wordpress.org/system-requirements-check/trunk@883617 b8457f37-d9ea-0310-8a92-e5e31aec5664