bug#57815: 29.0.50; loaddefs-generate docstring: DIR vs. DIRS

[Eli Zaretskii]

> From: Michael Heerdegen <michael_heerdegen@web.de>
> Date: Thu, 15 Sep 2022 04:55:13 +0200
> 
> the first arg of loaddefs-generate has the name DIR but the first
> sentence names it DIRS.
> 
> While that argument can be a dir or a list of dirs, this first sentence
> breaks our rules.

Yes, should be fixed now.

> Would it be worth to name the argument "DIR-OR-DIRS" for discoverability
> - or should the docstring just say
> 
> "Generate loaddefs files for Lisp files in DIR.
> DIR can be either a single directory or a list of directories.
> [...]" ?

I made it say

  Generate loaddefs files for Lisp files in one or more directories given by 
DIR.