luci-app-nut: improve confusing driver option text

luci-app-nut: improve confusing driver option text

Some driver options were noted as '(Display)' even though they are
added to the `ups.conf` configuration file (this is because the drivers
use them in the messages they emit). Since not all drivers support these
options and it is quite a large job to manage the which options apply
to which of the many drivers for nut, for now we add informational
text to inform the user of the situation.

Discussed in #8200 mfr, model fields not valid on usbhid-ups driver
and #8241.

As noted in the latter's comments, more than one driver uses the
problematic options, so the solution is not as simple as hiding the
options for any driver except that one.

Signed-off-by: Daniel F. Dickinson <redacted>