Added prerequisites to Harbor

Author: carlosadiegosysdig

resources/harbor/INSTALL-v2.2.md

@@ -1,2 +1,9 @@
-# Installing the exporter
-Harbor is already instrumented so you don't have to add any extra exporter.
+# Prerequisites
+Harbor is already instrumented so you don't have to add any extra exporter.
+
+As seen in the Harbor documentation page [Configure the Harbor YML File](https://goharbor.io/docs/main/install-config/configure-yml-file/), to make Harbor expose an endpoint for scraping metrics, you need to set the 'metric.enabled' configuration to 'true'.
+
+If you install Harbor with Helm, you need to use the following flag:
+```
+--set 'metrics.enabled=true'
+```