[virtio 1.3] Change freeze has started

[Cornelia Huck <cohuck@redhat.com>]

As outlined in
https://lists.oasis-open.org/archives/virtio/202304/msg00036.html ff.,
as part of the release process for the 1.3 version of the virtio spec,
we have now entered change freeze. This means that the only changes to
the main virtio branch will now be those needed for the 1.3 release
(administrative and editorial.) We hope to have something ready for vote
in August.

For any changes for the next virtio release, please target the
virtio-1.4 branch, which will eventually merge back into the main
development branch once 1.3 has been released. (This next release might
not be called 1.4, but that should be inconsequential here.)

virtio 1.3 timeline:

Development

July 3rd: feature freeze (github issue
and change on list)

August 2nd: change freeze (all voted
upon)

virtio-next development branch opens              <---- we are here

August: prepare draft

August 31st (latest): draft voted upon by TC

September: public review period

October: addtl public review period, if needed

October (November): 1.3 released

merge virtio-next development branch