bug#55688: Incorrect documentation of "string-pad"

[Eli Zaretskii <eliz@gnu.org>]

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> Date: Fri, 27 May 2022 18:13:53 -0400
> From: emacs--- via "Bug reports for GNU Emacs,
>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> 
> Documentation of "string-pad" function says following (highlighting is
> mine).
> 
> 	@defun string-pad string length &optional padding start
> 
> 	Pad @var{string} to the be of @var{length} using @var{padding} as the
> 	padding character (defaulting to the space character).
> 
> 	If @var{string} is shorter than @var{length}, no padding is done.
> 	^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> 
> 	If @var{start} is @code{nil} (or not present), the padding is done to the
> 	end of the string, and if it's non-@code{nil}, to the start of the
> 	string.
> 
> => https://git.savannah.gnu.org/cgit/emacs.git/tree/doc/lispref/strings.texi#n445
> 
> I don't think highlighted line is correct. I matches neither behaviour of
> emacs:
> 
> 	=> (string-pad "foo" 12)
> 	"foo         "
> 
> nor what is usually meant by word "padding". I believe issue can be
> solved by s/shorter/longer or removing highlighted line at all.

It was more than that.  Now fixed on the release branch.

Thanks.