[Virtio-msg] Notes and fixed up PR from meeting on 2025/10/16

All,

The notes from the meeting are here: https://linaro.atlassian.net/wiki/spaces/HVAC/pages/30311874561/2025-10+Upda...

PR #25 has been redone to include Bertrand's commits as well as my own. https://github.com/Linaro/virtio-msg-spec/pull/25

I am most interested to know everyones opinion on the removal of the redundant length fields. I am 60/40 against.

Thanks, Bill