Adds developer/maintainer documentation

DESCRIPTION

Checklist

• Manually verified passing unit tests for this branch locally by running bin/run_docker_tests.sh
  • Yes, this is a pain, but GitLab doesn't run reasonably within a docker container in a normal CI pipeline
  • See bin/run_docker_tests.sh --help for faster/iterative testing options
• Paste local test output
• Add a CHANGELOG.md entry

Local Test Output

/bin/run_docker_tests.sh output

OUTPUT HERE