Merge pull request #29 from serokell/contributing

Create CONTRIBUTING.md

Author: yorickvP

CONTRIBUTING.md

@@ -0,0 +1,7 @@
+# Contribution Guidelines
+
+We welcome issues and pull requests at https://github.com/serokell/nixfmt.
+
+We use stylish-haskell to format our code. Make sure to format your
+contributions with it. It is available within the `nix-shell` and it should pick
+up the configuration from the repository automatically.