[website] updated helm install page (#139)

CHANGES:
- added optional configuration for Prometheus integration

website/content/en/docs/installation/helm/_index.md

@@ -0,0 +1,50 @@
+---
+title: "Using Helm"
+linkTitle: "Using Helm"
+weight: 20
+type: "docs"
+tags: ["setup"]
+description: >
+  How to deploy with Helm charts
+---
+
+To install CAP operator components, we recommend using the [Helm chart](https://github.com/sap/cap-operator-lifecycle/tree/main/chart) that is published as an OCI package at `oci://ghcr.io/sap/cap-operator-lifecycle/helm/cap-operator`.
+
+## Installation
+
+Create a namespace and install the Helm chart in that namespace by specifying the `domain` and the `dnsTarget` for your subscription server, either 
+
+- #### As command line parameters:
+  ```bash
+  kubectl create namespace cap-operator-system
+  helm upgrade -i -n cap-operator-system cap-operator oci://ghcr.io/sap/cap-operator-lifecycle/helm/cap-operator --set subscriptionServer.domain=cap-operator.<CLUSTER-DOMAIN> --set subscriptionServer.dnsTarget=public-ingress.<CLUSTER-DOMAIN>
+  ```
+
+- #### Or as a `YAML` file with the values:
+  ```bash
+  kubectl create namespace cap-operator-system
+  helm upgrade -i -n cap-operator-system cap-operator oci://ghcr.io/sap/cap-operator-lifecycle/helm/cap-operator -f my-cap-operator-values.yaml
+  ```
+  In this example, the provided values file, `my-cap-operator-values.yaml`, can have the following content:
+  ```yaml
+  subscriptionServer:
+    dnsTarget: public-ingress.<CLUSTER-DOMAIN>
+    domain: cap-operator.<CLUSTER-DOMAIN>   
+  ```
+
+## (Optional) Setup Prometheus Integration for _Version Monitoring_
+
+To use the Version Monitoring feature of the CAP Operator, a [Prometheus](https://prometheus.io/) server URL can be provided to the CAP Operator. When installing the CAP Operator using the Helm chart, the following values can be specified in the values:
+```yaml
+controller:
+  versionMonitoring:
+    prometheusAddress: "http://prometheus-operated.monitoring.svc.cluster.local:9090" # <-- example of a Prometheus server running inside the same cluster
+    promClientAcquireRetryDelay: "2h"
+    metricsEvaluationInterval: "30m" # <-- duration after which version metrics are evaluated
+```
+When the controller is started, the operator will try to connect to the Prometheus server and fetch [runtime information](https://prometheus.io/docs/prometheus/latest/querying/api/#runtime-information) to verify the connection. If the connection is not successful, it will be retried after the duration specified as `controller.versionMonitoring.promClientAcquireRetryDelay`. Check default values for these attributes [here](helm-values.md).
+
+{{% alert title="Note" color="info" %}}
+- When connecting the controller to a Prometheus server running inside the cluster, please ensure that `NetworkPolicies` required for connecting to the service in the namespace where Prometheus is running are also created.
+- If the Prometheus service is configured to use TLS, the relevant CA root certificates which need to be trusted can be mounted as volumes to the controller.
+{{% /alert %}}

website/content/en/docs/installation/helm/helm-values.md

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+---
+title: "Helm Values"
+linkTitle: "Helm Values"
+weight: 10
+type: "docs"
+tags: ["setup"]
+description: >
+  Discover all values supported by the latest CAP Operator helm chart 
+---
+
+{{% include "includes/chart-values.md" %}}