Addition to Semantics agenda for 18 June

Sam and I have written a first draft of an accessibility primer
<https://mathml-refresh.github.io/mathml/docs/accessibility>.

I am scheduled to talk about that at the APA WG meeting next Wednesday and
would like to go over it briefly and get some feedback on it before
discussing it with the APA group.

If you get a chance, please take a look at it and let me know what you
think. The "Semantic Markup" and "Examples" sections are not finished, but
there is a lot there (too much?) not counting those sections.

     Neil