Where did the Developer's Guide go?

I’m trying to contribute code, but I’m facing some challenges in getting the code setup in the first place. An example of this can be seen in my other post Failing to run tests for camunda-bpm-webapp. I had to do similar workarounds to get camunda-bpm-platform to compile and run in IDEA. I was hoping the Developer’s Guide would shed some light on these issues.

I got it somewhat working right now, but I was hoping for some recommended setup page (e.g. I noticed Eclipse settings in a repo, so I’m guessing the Camunda team is working with Eclipse).