date to @timestamp

changed @timestamp to the actual timestamp of the log entry

logstash/conf.d/20-dns-syslog.conf

@@ -7,6 +7,11 @@ input {
 }
 
 filter {
+  
+  date {
+      match => [ "date", "MMM  d HH:mm:ss" ]
+  }
+
   if "pihole" in [tags]{
     grok {
       patterns_dir => ["/etc/logstash/patterns/"]