doc: add new documentation rule

Add 80 characters limit to docs.
Change docs to fit 80 characters per row.

Backport-PR-URL: https://github.com/nodejs/node/pull/19189
PR-URL: https://github.com/nodejs/node/pull/18726
Fixes: https://github.com/nodejs/node/issues/18703


Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: Anatoli Papirovski <apapirovski@mac.com>