news: add the ports reset script

Following the freeze of the ports tree announced on 2026-07-22, this
script may be used to correct branches that contain the offending
object. Note that it contains some commit hashes that need to be
replaced if your local branch has changes included that alter these;
instructione are included inside.

The script was originally written by glebius@, with slight modifications
by kevans@ and dhw@.

Reviewed by: adrian, dhw, glebius, lwhsu (all previous version)
Differential Revision: https://reviews.freebsd.org/D58417