doc: add Gibson Fahnestock to Release team

PR-URL: https://github.com/nodejs/node/pull/16620
Refs: https://github.com/nodejs/TSC/issues/350


Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Myles Borins <myles.borins@gmail.com>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>