doc: revise LTS text in collaborator guide

PR -> pull request
can -> might (to be clear it's about possibility)
were -> do for active/passive parallel structure

PR-URL: https://github.com/nodejs/node/pull/37527


Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>
Reviewed-By: Gerhard Stöbich <deb2001-github@yahoo.de>