doc: mark settings as optional and add callback
The settings are currently not required and the callback was not documented so far.
This is an alternative to https://github.com/nodejs/node/pull/26811.
Refs: https://github.com/nodejs/node/pull/26811
Checklist
-
make -j4 test
(UNIX), orvcbuild test
(Windows) passes -
tests and/or benchmarks are included -
documentation is changed or added -
commit message follows commit guidelines