deleting old readme

git-svn-id: https://plugins.svn.wordpress.org/article-difficulty-level/trunk@819523 b8457f37-d9ea-0310-8a92-e5e31aec5664
New readme file added 2.1.1

git-svn-id: https://plugins.svn.wordpress.org/article-difficulty-level/trunk@819524 b8457f37-d9ea-0310-8a92-e5e31aec5664