Thanks for taking the time to read this! This doc contains guidelines and resources for contributing. It's not too complete but I'll add to it.
Feel free to report bugs in the issues tracker. There are templates when creating a new issue to help you get started. Try to search for existing bugs first, the keyword search is quite good.
You can also suggest features and improvements in the issue tracker as well.
Development docs are on the github page for this repo. The site will have instructions for setting up a build environment including instructions on how to debug a local setup as well as an overview of the project itself.
I try to keep it as up to date as possible but like all docs, they tend to get outdated. If something is out of date feel free to raise an issue about it.