The "Reviewing Pull Requests" section in the contributing guide is not written in the contributor's perspective

[joyeecheung]

Just reading through #17285 (comment) and discovered that we don't seem to have a document written in a new contributor's perspective about what a PR needs to proceed or to be blocked. I've split the contributing guide into separate documents and the part about reviews seem to be written in reviewers' perspective which is odd, considering we already have a collaborator guide that covers that:
https://github.com/nodejs/node/blob/master/doc/guides/contributing/pull-requests.md#reviewing-pull-requests

Opening this mostly to remind me to update (completely rewrite?) this part...

[BridgeAR]

Ping @joyeecheung

[apapirovski]

I'm going to close this given the lack of movement. It's possible this isn't actually needed?