Document required scopes for personal access tokens (PAT)

### TL;DR

Using release-please-action with the default GITHUB_TOKEN works, but this has the caveat that it doesn't trigger other workflows (e.g. a workflow to test the proposed release, or required workflows to validate commit messages). I would like to move to a personal access token, but there is no documentation about the required scopes for a PAT.

What are the required scopes?

If I can figure this out or get hints from the maintainers, I would be happy to submit a docs PR.

### Expected behavior

_No response_

### Observed behavior

_No response_

### Action YAML

```yaml
# N/A
```

### Log output

_No response_

### Additional information

_No response_