fix readme

git-svn-id: https://plugins.svn.wordpress.org/ebook-store/trunk@883493 b8457f37-d9ea-0310-8a92-e5e31aec5664
fix readme

git-svn-id: https://plugins.svn.wordpress.org/ebook-store/trunk@883494 b8457f37-d9ea-0310-8a92-e5e31aec5664