Re: completion-auto-help

[Richard M. Stallman]

    complete.el extends the meaning of the variable so that a non-nil non-t
    value means "show the help but only on the second attempt to complete".
    I.e. if TAB finds nothing to complete, the first TAB will just say "[Next
    char not unique]" without bringing up the *Completions* buffer, and the
    second TAB will then bring up the *Completions* buffer.
    It happens to be my favorite behavior.

Could you document this?  It seems not to be documented now,
not even in complete.el.  It would be convenient to document this
in the doc string of that variable.