doc: move kfarnung to collaborator emeriti list

I emailed with Kyle and they indicated a move to emeritus would be
ok at this point in time.

PR-URL: https://github.com/nodejs/node/pull/34258


Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Anto Aravinth <anto.aravinth.cse@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>