doc: add onboarding details for ambassador program

PR-URL: #55284
Reviewed-By: Moshe Atlow <moshe@atlow.co.il>
Reviewed-By: Yagiz Nizipli <yagiz@nizipli.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Paolo Insogna <paolo@cowtech.it>
Reviewed-By: Rafael Gonzaga <rafael.nunu@hotmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Ulises Gascón <ulisesgascongonzalez@gmail.com>
Reviewed-By: Michael Dawson <midawson@redhat.com>

Author: marco-ippolito

doc/contributing/advocacy-ambasador-program.md

@@ -39,6 +39,15 @@ a discussion issue with the nomination in
 [nodejs/collaborators](https://github.com/nodejs/collaborators/)
 titled `Nomination X to be an Ambassador`, where X is the name of the person
 being nominated.
+If there is no objection within 14 days, the nomination is approved.
+
+## Onboarding
+
+To onboard an ambassador, a member of the TSC will:
+
+* \[] Add the ambassador to the nodejs/ambassadors team.
+* \[] Add the ambassador to the nodejs/ambassadors `README.md`.
+* \[] Add the ambassador to the OpenJS Slack channel.
 
 ## Reviewing content