Agree that page is not so useful at this point! although the link you referenced appears as “legacy help” - so not a huge problem…
more of an issue is https://doc.sccode.org which is for 3.12 it would be nice if this were up to date or perhaps simply link back to https://docs.supercollider.online which should be soon (or is now?) the official online source?
All others SuperCollider docs are served by private individuals or institutions - if they become outdated/unmaintained there is nothing we can do about it b/c we often don’t know who can be contacted about them.