feat: Hide Server Version

ref: #33 closes #31

Author: jon-nfc

includes/etc/bind/conf.d/options.conf

@@ -2,6 +2,7 @@
 options {
     directory "/var/bind";
 
+    version "unknown";
 
     listen-on { 127.0.0.1; };
     listen-on-v6 { none; };