doc: mention adding YAML for APIs in PR contributing guide
PR-URL: https://github.com/nodejs/node/pull/35459
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Mary Marchini <oss@mmarchini.me>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
