Document difference between public/private repo's for organizational runners

UPDATE

A organizational runner won't take on a job to run on a public repo, unless its explicitly asked via a quite hard to find checkbox: see https://github.com/actions-runner-controller/actions-runner-controller/issues/732#issuecomment-907908875.

Action point to close issue: document it.

There is a troubleshooting section to fix common mistakes, but there is no debugging section to help users figure out how to identify what could have gone wrong.

I'd be happy to contribute updating such documentation if someone can help me on my way to debug my situation better, I've been stuck at this for ~6 hours or so now.

My specific situation in need of debugging advice

1. I've created an app within Org A, and only granted the repository level permission listed for organizational runners.
2. I've installed the app in Org B
3. I've created a k8s secret with credentials to use
4. I've got pods running and ready representing from a RunnerDeployment, and they are listed in Org B as idle.
5. I've created a PR that reference self-hosted, but the job isn't picked up by the org runner ,and my runner is stuck with the following logs as read via kubectl.

√ Connected to GitHub

2021-08-18 20:29:02Z: Listening for Jobs

Version details

• Chart 0.19.0
• summerwind/action-runner:latest (Trasnaltes to v2.280.2-ubuntu-20.04-b6465c5 thanks to imagePullPolicy: Always)
• A k8s cluster based on k3s that has a Arm64 architecture on its RaspberryPi 4B computers.

Start with the existing troubleshooting section and the linked issue comment describing the organizational-runner behavior. Document the difference between public and private repositories, including the required workflow setting, and add debugging guidance for runners that remain idle; the issue is done when these cases are explained clearly.