Update CONTRIBUTING.md

Author: nicolaskruchten

CONTRIBUTING.md

@@ -1,6 +1,12 @@
 # Contributing to Plotly.js
 
-Thanks for your interest in contributing to Plotly.js!
+Thanks for your interest in contributing to Plotly.js! We are actively looking for
+diverse contributors, with diverse background and skills.
+
+## Code of Conduct
+
+Please check out our [Code of Conduct](CODE_OF_CONDUCT.md). Don't tl:dr; it
+but the general idea is to be nice.
 
 ## Plotly.js vs Plotly.py and Plotly.R