Hello there!
I wanted to look up documentation for some ES.later features which I wasn’t able to find. Of course no browser has implemented any of them yet. So would it make sense to at least make a page with a note about that? It would work like “Non-standard”, “obsolete” or “deprecated”. Additional to this, there could be a version label for everything to show when it was added (acts like a shortcut for the " Specifications" section to which an anchor could be added).
Best regards