Add a Contributing.md

Author: mythz

CONTRIBUTING.md

@@ -0,0 +1,5 @@
+## Contributor License Agreement
+
+* Please sign the [Contributor License Agreement](https://docs.google.com/forms/d/16Op0fmKaqYtxGL4sg7w_g-cXXyCoWjzppgkuqzOeKyk/viewform) in order to have your changes merged.
+
+See the [Contributing Wiki](https://github.com/ServiceStack/ServiceStack/wiki/Contributing) to learn how you can Contribute!