minio-hs-1.0.0: CONTRIBUTING.md

# Contributors Guide
* Fork minio-hs.
* Create your feature branch (`$ git checkout -b my-new-feature`).
* Hack, hack, hack...
* Commit your changes (`$ git commit -am 'Add some feature'`).
* Do test build (`$ stack test`).
* Push to the branch (`$ git push origin my-new-feature`).
* Create new Pull Request.