doc: suggest not to throw JS errors from C++

Also provide an example on how to use internal/errors
to handle errors in C++.

PR-URL: https://github.com/nodejs/node/pull/18149
Refs: https://github.com/nodejs/node/issues/18106


Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Jon Moss <me@jonathanmoss.me>
Reviewed-By: Weijia Wang <starkwang@126.com>
Reviewed-By: Daniel Bevenius <daniel.bevenius@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>