You can contribute through Pull Requests (PRs) or creating Issues.
PRs
There really isn't set standards for PRs being taken in. Any sort of modifications to improve the code is welcome. We just ask that is tested and does not introduce any new warnings. Generally it's preferable if the code comes from the Linux RMI4 if applicable.
Issues
Provide a log and concise description of the issue. Logs can be gotten using log show --last boot | grep -i voodoo > ~/Desktop/RMILog.txt, which takes logs from when the system last booted and filters them for this kext, before placing it on the desktop.