pkg_add -m/parse_cross() documentation

[Edgar Fuß <ef%math.uni-bonn.de@localhost>]

I was going to add an option to pkg_add to allow it to install packages 
(meant for use with -P, of course) for a different NetBSD version, found out 
where to add it, looked at -current to see an even more general approach is 
already there.

But there seems to be no documentation on this feature (besides the one in *.c 
format).

If I read that documentation correctly, I would need to use
	-m "NetBSD/eniac 0.8.15"
is there any reason for not allowing
	-m "NetBSD 0.8.15"
other than it appears strange for an option originally specifying the arch 
only to possibly specify everything /but/ the arch?