[#4105] Update docs for Postgresql

docs/docs/apps/postgresql.md

@@ -7,8 +7,20 @@ sidebar_label: Postgresql
 
 By install ing the Postgresql component, a complete Postgresql server will be installed with a Service that can be reached on the `postgresql` host and port `5432` from inside the Kubernetes cluster. At the moment the Postgresql instance is only available from inside the cluster and it cannot be reached from the outside.
 
+The Postgresql Helm chart can be installed either from the Catalog in the `Control Center` or by running `helm install`:
+
+```
+helm repo add airy https://helm.airy.co
+helm repo update
+helm install postgresql airy/postgresql
+```
+
+The default version is `15.1` but this can be modified by overwriting the `--set version` value, when deploying the Helm chart.
+
 To retrieve the administrative Postgresql password run:
 
 ```
 kubectl get secret postgresql -o jsonpath='{.data.postgresql-password}' | base64 -d
 ```
+
+Note that the password changes everytime that the helm chart is updated. Would be best to use it as an environmental variable in the pod, mounted directly from the `postgresql` secret.