The programmer’s manual really needs some work - in particular there are tons of new containers and support functions that ought to be mentioned. It seems like every few weeks I “discover” some new facility in ADT/ or Support/ and I think “Gee, that looks really useful - I wonder how long that’s been there?” (The most recent example being the ANSI terminal support in raw_ostream).
You're right, that would be great!
Alas, if it's not documented when the change is made, it's probably not going to get documented. Ever. It's the same story with the release docs.
Blame the lazy committer, hope for future improvements, read the commits to figure out what's going on and move on