Update README.md

Author: Pomax

README.md

@@ -56,3 +56,7 @@ With the test server is running, the following urls are good to know:
 * [http://localhost:3000/ref](http://localhost:3000/ref) - reference testing page
 * [http://localhost:3000/perf](http://localhost:3000/perf) - performance testing page
 * [http://localhost:3000/processing-helper.html](http://localhost:3000/processing-helper.html) - utility page for converting/running Processing code
+* 
+### Contributing to Processing.js
+
+Please read ["how to contribute to Processing.js"](Contribute.md) for how you can contribute, and what code of conduct is expected to be followed.