description on --with-zonezfile in README

[Koh-ichi Ito]

Hello,

README in nsd-2.1.5 says 

  --with-zonesfile=path

        Pathname to the NSD list of zones, default /etc/nsd/nsd.conf

in "2.2 Configuring NSD" section.

I guess "nsd.conf" should be "nsd.zones".

How?

						Koh-ichi Ito