[patch] document procedure to add a new ports category to Committer's Guide

[Mark Linimon]

> Can't we just have people fix this directly for the usual case, and have
> a "submit a doc PR if you feel uncomfortable about doing that" as an
> option?

I don't really have a problem with this.  I note, however, that
recently the doc guys have taken a few "arrows in the back" as
we say colloquially here, from ports committers, in terms of
checkins to the handbooks that weren't 100%.

Basically common sense and courtesy ought to be the determinants.
I'll accept any rewording.  I'm far more interested in getting
a complete list of the things that need to be changed, than in
promulgating procedures.

mcl