sysutils/nut*: Alternate upslog support for multiple UPSs

Add  sample rc script to allow a user to copy a sample rc script to
rc.d, allowing the user to use multiple instances of upslog(8) with
multiple instances of the rc script to log multiple UPSs on the same
system.

The sample rc script was provided by vvd@unislabs.com.

PR:		265963
Reported by:	vvd@unislabs.com
Submitted by:	vvd@unislabs.com