Note about capping deployments to ~100 replicas

[Djiit]

Fixes #1101

[toast-gear]

Let me have a think about the best way to document this. In the future we want Stateful Runners to take a more prominent place in the docs and this will be relevant to them too.

[toast-gear]

I think it's probably best to put it as a second > note after:

> Since the release of GitHub's [`workflow_job` webhook](https://docs.github.com/en/developers/webhooks-and-events/webhooks/webhook-events-and-payloads#workflow_job), webhook driven scaling is the preferred way of autoscaling as it enables targeted scaling of your `RunnerDeployment` / `RunnerSet` as it includes the `runs-on` information needed to scale the appropriate runners for that workflow run. More broadly, webhook driven scaling is the preferred scaling option as it is far quicker compared to the pull driven scaling and is easy to setup.

Additionally could could you change it to:

> If you are not using GHES, and so can't set your rate limit budget, it is recommended to have fewer than 100 replicas per deployment to avoid exhausting your budget.

Cheers pal

[genisd]

not that I have anything to say. as a symbolic gesture here is my approval :)

[toast-gear]

This hasn't been merged on purpose, it will get merge after the next release which is imminent. The next release includes caching of requests so this warning won't hold true. It will need to highlight this applies to controller version < v0.22.0 in the style of the other version warnings:

> If you are using controller version => [v0.22.0](https://github.com/actions-runner-controller/actions-runner-controller/releases/tag/v0.22.0) and you are not using GHES, and so can't set your rate limit budget, it is recommended that you use 100 replicas or fewer to prevent being rate limited

Merging it now will just cause confusion and will need updating as soon as the next release is out.

[toast-gear]

@Djiit there were various changes to the readme for the latest release. If you could resolve the conflicts in this PR and change the message to be the below we can get this merged:

> If you are using controller version < [v0.22.0](https://github.com/actions-runner-controller/actions-runner-controller/releases/tag/v0.22.0) and you are not using GHES, and so can't set your rate limit budget, it is recommended that you use 100 replicas or fewer to prevent being rate limited

[Djiit]

@toast-gear something like this ?