doc: use more consistent formatting for deprecations

Most deprecations do not end with a full-stop/period, but three of them
do. Well, not anymore after this change.

PR-URL: https://github.com/nodejs/node/pull/39218


Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>