MOVING README files to README.md

git-svn-id: https://silverstripe-ecommerce.googlecode.com/svn/modules/ecommerce_discount_coupon/branches/2.4@4909 950b781c-c544-efab-2f99-90083ee69683
MOVING README files to README.md

git-svn-id: https://silverstripe-ecommerce.googlecode.com/svn/modules/ecommerce_discount_coupon/branches/2.4@4910 950b781c-c544-efab-2f99-90083ee69683