add missing default in documentation
@@ -395,7 +395,7 @@ Prevent NSD from replying with the identity string on CHAOS class
queries. Default is no.
.TP
.B drop\-updates:\fR <yes or no>
-If set to yes, drop received packets with the UPDATE opcode.
+If set to yes, drop received packets with the UPDATE opcode. Default is no.
.TP
.B use\-systemd:\fR <yes or no>
This option is deprecated and ignored. If compiled with libsystemd,
