added screenshots

git-svn-id: https://plugins.svn.wordpress.org/conekta-woocommerce/trunk@994053 b8457f37-d9ea-0310-8a92-e5e31aec5664
added screenshots attempt 2

git-svn-id: https://plugins.svn.wordpress.org/conekta-woocommerce/trunk@994054 b8457f37-d9ea-0310-8a92-e5e31aec5664