Fixed a typo in knot.full.conf

Refs #1997

samples/knot.full.conf

@@ -196,7 +196,7 @@ zones {
     # Possible values: <1..INT_MAX> (seconds)
     # Default value: inherited from zones.zonefile-sync
     # It is also possible to suffix with unit size [s/m/h/d]
-    # f.e. 1s = 1 day, 1m = 1 minute, 1h = 1 hour, 1d = 1 day
+    # f.e. 1s = 1 second, 1m = 1 minute, 1h = 1 hour, 1d = 1 day
     zonefile-sync 1h;
 
     # XFR master server