doc: document 'inherit' option for stdio (non-shorthand)

PR-URL: https://github.com/nodejs/node/pull/22309
Fixes: https://github.com/nodejs/node/issues/22297


Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>