[tz] draft of change summary for next tz release

[Paul Eggert]

Alan Barrett wrote:
> we have not been aware of such controversial changes before.

And that's the main difference.  In the past, development
was made privately, with intermediate patches sometimes
emailed to the list but often not, and the only real notice of a change
was a new release.  Now that I've been doing things on a public
github site, we're getting lots more comments from people affected
by changes as they're being considered.  So even though the development
practice is roughly the same as before, and even though the proposed
set of changes is far less intrusive than some previous changesets,
people are understandably concerned by seeing the details of a process
that were formerly invisible.

I continue to be tempted to go back to the old way of keeping
development private, not only because it'd be less work for me,
but because I suspect it'd be less work for everyone else.