Add Prometheus annotations to nginx-controller setup guide.

SMPROD-7716

Author: Jesus Samitier

resources/nginx-ingress/INSTALL.md

@@ -1,7 +1,7 @@
 # Installing the exporter
-Nginx ingress controller is already instrumented so you don't have to add any extra exporter. However, ensure that your nginx ingress controller is already exposing these metrics.
+Nginx ingress controller is already instrumented so you don't have to add any extra exporter. However, ensure that your nginx ingress controller is already exposing these metrics. Don't forget to include the `prometheus.io/port` and `prometheus.io/scrape` annotations.
 
-For example if you are deploying your nginx ingress controller with helm, make sure you have these values.
+For example if you are deploying your nginx ingress controller using the helm chart from Kubernetes, the values would be:
 
 ```yaml
 controller:
@@ -10,6 +10,7 @@ controller:
     enabled: true
   podAnnotations:
     prometheus.io/port: "10254"
+    prometheus.io/scrape: "true"
 ```
 
 # Sysdig Agent configuration