doc: revise Collaborator material in GOVERNANCE.md

* Reduce passive voice
* Shorter and simpler sentences

PR-URL: https://github.com/nodejs/node/pull/27103


Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Yongsheng Zhang <zyszys98@gmail.com>
Reviewed-By: Yuta Hiroto <hello@hiroppy.me>