Document the res_findzonecut2 function and parameters.
From the original PR:
The resolver library routine called res_findzonecut2 which is part
of libc isn't documented on any man page... at least none that I've
found. But this is a useful function, and should have a man page.
The man page for resolver(3) should be enhanced to also
document res_findzonecut2.
PR:126484