Replace CONTRIBUTING.md with standard template for chef-server

Signed-off-by: cgunasree08 <Chintha.Gunasree@progress.com>

Author: cgunasree08

CONTRIBUTING.md

@@ -1 +1,3 @@
-Please refer to https://github.com/chef/chef/blob/master/CONTRIBUTING.md
+# Contributing to a Progress Chef Infra Server Project
+
+Thanks you for your interest in contribuing to this project! It is part of the larger Progress Chef Infra Server project. Contribution guidelines can be found at [Contributing to Progress Chef Infra Server](https://chef.github.io/chef-oss-practices/projects/chef-server/contributing/).