docs: Add documentation about Helm Chart

Author: codablock

docs/install.md

@@ -16,4 +16,10 @@ kubectl create ns kluctl-system
 kustomize build "https://github.com/kluctl/template-controller/config/install?ref=v0.5.3" | kubectl apply -f-
 ```
 
-Helm Charts will be supported in the near future.
+## Helm
+A Helm Chart for the controller is also available [here](https://github.com/kluctl/charts/tree/main/charts/template-controller).
+To install the controller via Helm, run:
+```shell
+$ helm repo add kluctl https://kluctl.github.io/charts
+$ helm install template-controller kluctl/template-controller
+```