docs: final doc changes + v0.23.0 release notes

[toast-gear]

Refs: #1390

[lovesegfault]

I would appreciate it if the following were included in the next release:

• Force restartPolicy "Never" to prevent runner pods from stucking in Terminating when the container disappeared #1395
• feat: Support arbitrarily setting privileged: true for runner container #1383

[mumoshu]

@lovesegfault Hey. Sorry! But we do quite extensive manual tests before releasing so adding random changes to an already planned release isn't very feasible. Doing so would only suffer us maintainers and hence also you users who will be submitting a lot of questions to be answered if it doesn't work well after the release!

To improve the situation, you could either sponsor this project and maintainers so that we can set up an automated e2e test infrastructure, or contribute E2E tests to every new feature.

[mumoshu]

I greatly appreciate your efforts @toast-gear! Let's merge this and cut 0.23.0 now!