doc: move `NODE_MODULE_VERSION` in release guide

Move the section on `NODE_MODULE_VERSION` into the section for
major releases as it should only be updated for a major release.
Add a note to remove the `-pre` suffix from the registry for the
release commit.

PR-URL: https://github.com/nodejs/node/pull/39544


Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Beth Griggs <bgriggs@redhat.com>
Reviewed-By: Danielle Adams <adamzdanielle@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>