doc: mark StackOverflow as unofficial

[fhinkel]

We're listing StackOverflow as a place for support in our README.md. Following the discussion in #18191, we should make it clear that the StackOverflow entries are not moderated by the Node.js Foundation.

[ckotzbauer]

@fhinkel Can I pick this up?

[JosephLeon]

I tried pushing up a fix for this but I'm getting:

remote: Permission to nodejs/node.git denied to JosephLeon.
fatal: unable to access 'https://github.com/nodejs/node.git/': The requested URL returned error: 403

[devsnek]

@JosephLeon you'll have to open a pr, check out https://github.com/nodejs/node/blob/master/CONTRIBUTING.md

[JosephLeon]

Ok, got a PR up here #19416

[fhinkel]

@JosephLeon Thanks for picking this up!

@code-chris sorry I didn't see your response early enough 😞

[ckotzbauer]

@fhinkel No problem 😉

[Trott]

Removing good first contribution on this since there's an open PR for it. #19416