[virtio 1.3] Reminder: Feature freeze coming up on July 1st

As outlined in  https://lists.oasis-open.org/archives/virtio/202304/msg00036.html  ff., we'll soon start the process of getting version 1.3 of the virtio spec released. As a first step, we'll enter feature freeze on July 1st. This means:  *** By July 1st, all not yet integrated features that are targeting 1.3 need to have at least a github issue open that is pointing to a patch (set) on the list. ***  This should hopefully give us enough time to conclude voting for those features before we enter change freeze on August 1st.  virtio 1.3 timeline:  Development
<-- we are here  July 1st: feature freeze (github issue and change on list)

August 1st: change freeze (all voted upon)  virtio-next development branch opens  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