bug#12492: Acknowledgement (24.2.50; Open vc-dir buffer easier and faster)

[Juri Linkov]

>> Regarding vc-dir, I see no better name than 'vc-dir-default'
>> meaning that it uses root-dir by default.
>
> But the question is not what the default is (which will be VC root), but
> whether to prompt the user or use that value right away.
>
> So I was thinking more along the lines of vc-dir-prompt-p. Or, more
> verbosely, vc-dir-prompt-for-directory.

'vc-dir-default' was intended both as option name and command name,
so users can choose either to customize it, or bind 'C-x v d' to command.

'vc-dir-root' may be a better name.