doc: expand fs.watch caveats

Document Windows specific fs.watch caveats.

Fixes: https://github.com/nodejs/node/issues/31702

PR-URL: https://github.com/nodejs/node/pull/32176


Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Masashi Hirano <shisama07@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>