Remove Deprecated Configuration from Sample nsd.conf

[Zixu Wu]

According to the manual page, the database feature has been removed and 
this option has no affect.

diff --git a/etc/nsd.conf b/etc/nsd.conf
index 1e86826372f..fd2ee9d8bdb 100644
--- a/etc/nsd.conf
+++ b/etc/nsd.conf
@@ -3,7 +3,6 @@
 server:
        hide-version: yes
        verbosity: 1
-       database: "" # disable database
 ## bind to a specific address/port
 #      ip-address: 192.0.2.53