log the host in nginx logs

setup/start/nginx/nginx.conf

@@ -15,7 +15,7 @@ http {
     # the collectd config depends on this log format
     log_format combined2 '$remote_addr - [$time_local] '
         '"$request" $status $body_bytes_sent $request_time '
-        '"$http_referer" "$http_user_agent"';
+        '"$http_referer" "$host" "$http_user_agent"';
 
     # required for long host names
     server_names_hash_bucket_size 128;