Merge pull request #4244 from beporter/add-contributing-pointer-to-readme

Add "contributing" pointers to GitHub readme

README.md

@@ -41,3 +41,9 @@ Our primary goal is to provide a structured framework that enables PHP users at
 
 [Roadmaps](https://github.com/cakephp/cakephp/wiki#roadmaps) - Want to contribute? Get involved!
 
+
+## Contributing
+
+[CONTRIBUTING.md](CONTRIBUTING.md) - Quick pointers for contributing to the CakePHP project
+
+[CookBook "Contributing" Section (2.x)](http://book.cakephp.org/2.0/en/contributing.html) [(3.0)](http://book.cakephp.org/3.0/en/contributing.html) - Version-specific details about contributing to the project