add "outgoing-interface" to sample unbound.conf

src/etc/unbound.conf

@@ -1,4 +1,4 @@
-# $OpenBSD: unbound.conf,v 1.6 2015/12/15 20:26:55 sthen Exp $
+# $OpenBSD: unbound.conf,v 1.7 2016/03/30 01:41:25 sthen Exp $
 
 server:
 	interface: 127.0.0.1
@@ -6,6 +6,11 @@ server:
 	interface: ::1
 	#do-ip6: no
 
+	# override the default "any" address to send queries; if multiple
+	# addresses are available, they are used randomly to counter spoofing
+	#outgoing-interface: 192.0.2.1
+	#outgoing-interface: 2001:db8::53
+
 	access-control: 0.0.0.0/0 refuse
 	access-control: 127.0.0.0/8 allow
 	access-control: ::0/0 refuse