bug#64425: [PATCH] Mention minibuffer-next-completion in completion-help

[Eli Zaretskii <eliz@gnu.org>]

> From: sbaugh@catern.com
> Date: Sun, 02 Jul 2023 16:31:21 +0000 (UTC)
> 
> * lisp/simple.el (completion-list-mode-map): Bind
> minibuffer-{next,previous,choose}-completion.
> (completion-setup-function): Mention bindings for
> minibuffer-{next,previous,choose}-completion.
> ---
>  lisp/simple.el | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/lisp/simple.el b/lisp/simple.el
> index 406f1008df3..59e1311eb2b 100644
> --- a/lisp/simple.el
> +++ b/lisp/simple.el
> @@ -9697,6 +9697,9 @@ completion-list-mode-map
>      (define-key map [right] 'next-completion)
>      (define-key map [?\t] 'next-completion)
>      (define-key map [backtab] 'previous-completion)
> +    (define-key map (kbd "M-<up>") 'minibuffer-previous-completion)
> +    (define-key map (kbd "M-<down>") 'minibuffer-next-completion)
> +    (define-key map (kbd "M-RET") 'minibuffer-choose-completion)
>      (define-key map "z" 'kill-current-buffer)
>      (define-key map "n" 'next-completion)
>      (define-key map "p" 'previous-completion)
> @@ -10093,8 +10096,8 @@ completion-setup-function
>  	(goto-char (point-min))
>  	(if (display-mouse-p)
>  	    (insert "Click on a completion to select it.\n"))
> -	(insert (substitute-command-keys
> -		 "In this buffer, type \\[choose-completion] to \
> +        (insert (substitute-command-keys
> +		 "Type \\[minibuffer-next-completion] and \\[minibuffer-previous-completion] to change completion, and \\[minibuffer-choose-completion] to \
>  select the completion near point.\n\n"))))))

Isn't this text too long for a single screen line?  If so, it will
cause an annoying "jumping" of the mode line.

Also, what about updating the documentation?