bug#65386: [PATCH] ; Refine some 'package-vc' docstrings

[Eli Zaretskii <eliz@gnu.org>]

> From: Eshel Yaron <me@eshelyaron.com>
> Cc: 65386@debbugs.gnu.org,  philipk@posteo.net
> Date: Sat, 19 Aug 2023 22:42:57 +0200
> 
> >> -(defcustom package-vc-selected-packages '()
> >> -  "List of packages that must be installed.
> >> -Each member of the list is of the form (NAME . SPEC), where NAME
> >> -is a symbol designating the package and SPEC is one of:
> >> +
> >> +(defcustom package-vc-selected-packages nil
> >> +  "List of packages to install from source.
> >
> > What is the significance of "from source" here?
> >
> 
> It's just for indicating that we're talking about VC packages
> specifically.  Does that make sense?

Then how about

  List of packages to install from their VCS repositories.

> >> +  "Send patch for REVISIONS to maintainer of the package PKG-DESC using SUBJECT.
> >
> > This should mention email, otherwise SUBJECT is confusing.  Maybe use
> > "Email" instead of "Send".
> 
> Alright, I made a couple more changes to this one.

Now you have lost the reference to SUBJECT.  Was that necessary?  We
generally try to mention all the mandatory arguments in the first line
of the doc string.  The sentence below seems to be squeezable into 79
columns:

  Email patches for REVISIONS to maintainer of package PKG-DESC using SUBJECT.

(Dropping articles is a frequent trick to make the first line fit.)