bug#32629: 26; `buffer-list-update-hook' doc string

[Drew Adams]

> > The doc string should not list the functions that run the hook.
> 
> Why not?

Same reason we don't do that elsewhere (do we?). Instead we
say, in the doc for each such function, that it runs the hook.

(Similarly, we don't list, in the doc for some function, all of the
functions that might call it.)

The most that could be done would be to list the functions
known, ahead of time, to run the hook. But even that is
counterproductive, IMO.

Let me ask: Why should this doc list the functions that run the
hook? And do you know of other places where we do that?