bug#46621: Copy line

[Eli Zaretskii]

> Cc: 46621@debbugs.gnu.org, Juri Linkov <juri@linkov.net>
> From: Mattias Engdegård <mattiase@acm.org>
> Date: Sat, 18 Jun 2022 20:02:58 +0200
> 
> -(defun duplicate-line (&optional n)
> -  "Duplicate the current line N times.
> +(defun duplicate-line-or-region (&optional n)
> +  "Duplicate the current line or region N times.

There's no need to include "or region" in the command's name and doc
string's first line.  We have quite a few commands that are sensitive
to the active region, and work on region when it's active.  We just
mention this in the doc string, and that's that.

> +If the region is inactive, the current line is duplicated.

Passive tense alert!

> +Otherwise, duplicate the region's contents.  The region remains
> +active afterwards.
> +If the region is rectangular, duplication is made on its right-hand side.

Another one!

Thanks.