I'd suggest to keep it. If we don't have time for a deep overhaul: please
just tell me which nodes of [1] have inaccurate information, and I'll add a
big warning "Note: The information on this page is out-of-date!" in each.
I would like to keep it, as it's the only documentation I'm aware of for the GNU regex APIs. (I guess it should really be in the glibc documentation, but it's not.)
Further updates can then occur by whoever has time to look into it.
I'm happy to prepare a patch in this case. I would simply remove all mention of syntax tables, as that functionality is no longer available.