Add a new rule to the committers: respect other contributors as well.

There has been plenty of discussion about how to actually ratify
such rules, but nobody has opposed this specific rule (which is a
good show of maturity btw).

In the end the conclusion is that this is not really any different from
the rest of the tree: If it makes sense: commit it, if it creats an
uproar, back it out and paint the bikeshed.

QED.

PR: 25783
Submitted by: Dan Langille <dan@langille.org>
Reviewed by: developers