First draft of new charter

I have created a first draft for our rechartering effort.
<https://w3c.github.io/mathml-docs/charter-2026.html> I also created an
issue for discussion of the charter
<https://github.com/w3c/mathml/issues/568>. Another avenue for discussion
is to draft a PR against the doc <https://github.com/w3c/mathml-docs>.

Discussion of the charter will be the priority of the meeting on Thursday
this week. Please try to find some time to read it and come prepared to
make suggestions. Time is short to move the rechartering forward.

     Neil