Republish properties&values API

[svgeesus]

The last /TR publication was 13 October 2020 and in particular, does not export the term "registered custom property" so a republication would be useful.

[svgeesus]

Also totally lacking a changes section.

[svgeesus]

I added the (fairly small) changes section.

@tabatkins @therealglazou @astearns @gregwhitworth ok to publish an updated working draft?

[svgeesus]

Publication requested 22 March, expected 26 March

[svgeesus]

Published 26 Mar 2024