bug#48764: mini-buffer completion

[jaime . escalante]

`completing-read' prompts a user to select from a set of candidates, providing
mini-buffer completion to narrow and complete the user input.

But the mini-buffer does not provide the user with any indication that he can 
use
the "up" and "down" keys to navigate a list of settings.  It would be 
beneficial to
introduce some kind of glyph or indicator in the mini-buffer to make the user 
aware
that arrow keys can be used, and be described in the manual.

    (if current-prefix-arg
        (let* ( ($major-mode
                   '("org-mode" "texinfo-mode" "emacs-lisp-mode"
                     "lisp-mode" "f90-mode"))
                ($mode (completing-read "Mode: " $major-mode
                         nil t nil 'ziggurat-bufr-history)) )
          (funcall (intern $mode)))
      (funcall (intern (or mode "org-mode"))))))