doc: update release guide with notes for major releases

Co-Authored-By: jasnell <jasnell@gmail.com>
Co-Authored-By: Rich Trott <rtrott@gmail.com>
Co-Authored-By: Beth Griggs <Bethany.Griggs@uk.ibm.com>

PR-URL: https://github.com/nodejs/node/pull/25497


Reviewed-By: Beth Griggs <Bethany.Griggs@uk.ibm.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>