bug#34949: 27.0.50; Docstring of `vc-deduce-fileset' incomplete

[Juri Linkov]

> The hook will allow us to move almost all of the new code to the place
> where its purpose is more obvious. And that's a good thing.

I think better to leave marking in vc-dir.el because it's the file
that deals with details of marking vc-dir files (using ewoc, etc.)

Requiring ewoc in vc.el would be inappropriate (supposing that the
hook will reside in vc.el)

>> Maybe then a shorter name vc-root-dir-action?
>
> The word "action" there seems to hold no particular meaning.
>
> vc-root-dir-with-dwim-selection, maybe?

Shorter names:

vc-dir-root-registered
or just
vc-dir-registered

Also there is a command 'vc-register' (C-x v i).
Its counterpart could be named 'vc-dir-register'
and will open a vc-dir buffer where only unregistered
files will be marked.