bug#47353: Numbered backups also need kept-new-versions else will grow out of control

[積丹尼 Dan Jacobson]

All I am saying is 'to acknowledge the hazards'... 'Advisory on
prolonged use'. 'Note about health effects of unattended use.'

For all the user knows reading
(info "(coreutils) Backup options")
maybe numbered backups even just means one backup, numbered ...1.