feat: add howto get response codes

content/nginx-one/nginx-configs/metrics/enable-metrics.md

@@ -21,3 +21,34 @@ The NGINX One Console dashboard relies on APIs for NGINX Plus and NGINX Open Sou
 ### Enable NGINX Open Source Stub Status API 
 
 {{< include "/use-cases/monitoring/enable-nginx-oss-stub-status.md" >}}
+
+### Include response codes
+
+To collect response codes in your log files, set a `status_zone` in descired `location` blocks. Here's an
+example that you could add to your NGINX configuration file:
+
+```nginx
+server {
+    listen 8080;
+
+    # - add response header
+    add_header "x-datapath-instance" "<datapath_id>" always;
+
+    default_type text/plain;
+
+    location / {
+        status_zone systest_loc_200;
+        return 200 "hello from datapath <datapath_id>\n";
+    }
+
+    location /4xx {
+        status_zone systest_loc_4xx;
+        return 400 "fake 400 from datapath <datapath_id>\n";
+    }
+
+    location /5xx {
+        status_zone systest_loc_5xx;
+        return 500 "fake 500 from datapath <datapath_id>\n";
+    }
+}
+```