Added more structure and explanation to the readme file

git-svn-id: https://plugins.svn.wordpress.org/bolcom-seller-widget/trunk@773948 b8457f37-d9ea-0310-8a92-e5e31aec5664
removed README.md

git-svn-id: https://plugins.svn.wordpress.org/bolcom-seller-widget/trunk@773949 b8457f37-d9ea-0310-8a92-e5e31aec5664