Comment by ShroudedNight

At one point I could have sworn they were sticking obsoletion notices in the header, but now I can only find them in the right side-bar:

https://datatracker.ietf.org/doc/html/rfc5245

I agree, that it would be much more helpful if made obvious in the document itself.

It's not obvious that "updated by" notices are treated in any more of a helpful manner than "obsoletes"