Create node/doc/guides/writing-docs.md

[bnb]

Currently we don't seem to have a guide for writing docs – or at least not one that I can find.

In the node/doc/guides directory, there seems to be examples for writing and running benchmarks and writing tests, but not one for writing docs.

I'd be happy to help take this on if someone could provide a list of bullets that would need to be addressed as steps to write docs within the file.

[vsemozhetbyt]

A file that can help a little: https://github.com/nodejs/node/blob/master/tools/doc/README.md
A file that can be mentioned in such a guide: https://github.com/nodejs/node/blob/master/doc/STYLE_GUIDE.md

[Trott]

Additional prior art from the archived docs repo:

• https://github.com/nodejs/docs/blob/master/CONTRIBUTING.md
• https://github.com/nodejs/docs/blob/master/GETTING-STARTED.md
• https://github.com/nodejs/docs/blob/master/ROADMAP.md (waaaay out of date but may be useful anyway?)

[Trott]

Also https://github.com/nodejs/docs/wiki/NodeJS-Documentation-Wiki