doc: add note about debugging worker_threads

PR-URL: https://github.com/nodejs/node/pull/30594
Fixes: https://github.com/nodejs/node/issues/30197


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>