doc: add POST_STATUS_TO_PR info to onboarding doc

[Trott]

Checklist

• documentation is changed or added
• commit message follows commit guidelines

Affected core subsystem(s)

doc

Description of change

POST_STATUS_TO_PR did not used to work.

Now it works.

Update the onboarding documentation accordingly.

[addaleax]

Commit message typo: did not used to

LGTM but got a question… does it ever make sense not to check that box?

[Trott]

@addaleax (Whoops, ignore previous comment, I misread your question.) I guess not. I suppose it might be worthwhile asking @nodejs/build to make that box checked by default and then we don't have to mention it at all in the onboarding doc!

[Trott]

@addaleax Updated the commit message. Thanks.

[Fishrock123]

@jbergstroem think we are ready to move forward with this or is there still stuff being worked on there?

[fhinkel]

Can we change the default for POST_STATUS_TO_PR to be checked? Seems easier than to add an extra instruction to the onboarding doc about actively turning it on.

[jasnell]

Yeah, I'd definitely prefer for post status to be on by default.

[jbergstroem]

I'd like to get some more time working with this if that's ok. ETA ~1w.

[mhdawson]

Same goes for me for having in on by default once we are ready.

[Trott]

Landed in fa1476c.

(We can update it again when the default switches to the box being checked. I expect to be updating the onboarding doc frequently anyway.)