Clarify zshaddhistory doc?

[Bart Schaefer <schaefer@xxxxxxxxxxxxxxxx>]

Under the entry for zshaddhistory:

     If any of the hook functions return a non-zero value the history
     line will not be saved, although it lingers in the history until
     the next line is executed allow you to reuse or edit it
     immediately.

What exactly does this mean?  There's no $zshaddhistory_functions array
so "any of the hook functions" is either a typo, or must refer to the
$preexec_functions hooks, which ought to be clearer.