doc: edit "Involving the TSC"

Edit the "Involving the TSC" section of the Collaborator Guide to reduce
passive voice, make things concise, etc.

PR-URL: https://github.com/nodejs/node/pull/26481


Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Yuta Hiroto <hello@hiroppy.me>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Beth Griggs <Bethany.Griggs@uk.ibm.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>