bug#50394: Improve "Completion List Mode" NEWS entry

[Stefan Kangas <stefan@marxist.se>]

Eli Zaretskii <eliz@gnu.org> writes:

> But the entry specifically talks about key bindings in that particular
> mode, so I still don't see why you think it should in a more general
> section.

This is often the problem with trying to find a good taxonomy: things
end up fitting in more than one category.  In this case, I am trying
to think about where a user would be most helped by seeing it.  I
believe this change will be visible enough all over Emacs to warrant a
more prominent location.

If that doesn't convince, I suppose it will have to be where it is.

The important part that remains is an explanation along the lines
"Improved navigation in the "*Completions*" buffer".  If this is
uncontroversial, I intend to add such a clarification.