Put commented minimal-reponses and refuse-any defaults into nsd.conf

so that the changed default will be pointed out to the admin by
sysmerge.
Idea & OK sthen

src/etc/nsd.conf

@@ -1,4 +1,4 @@
-# $OpenBSD: nsd.conf,v 1.11 2015/04/12 11:49:39 sthen Exp $
+# $OpenBSD: nsd.conf,v 1.12 2018/05/18 05:15:33 florian Exp $
 
 server:
 	hide-version: yes
@@ -10,6 +10,13 @@ server:
 #	ip-address: 192.0.2.53@5678
 #	ip-address: 2001:db8::53
 
+## make packets as small as possible, on by default
+#	minimal-responses: yes
+
+## respond with truncation for ANY queries over UDP and allow ANY over TCP,
+## on by default
+#	refuse-any: yes
+
 remote-control:
 	control-enable: yes