Adding link to the post in CONTRIBUTING.md
@@ -18,6 +18,8 @@ Talk about what you would like to do.
It may be that somebody is already working on it,
or that there are particular issues that you should know about before implementing the change.
+Once you are all set to go, [this "cookbook recipe" blog post](https://www.elastic.co/blog/a-cookbook-for-contributing-a-plugin-to-the-elastic-apm-java-agent) can guide you through.
+
### Submitting your changes
Generally, we require that you test any code you are adding or modifying.
