message: docs(selfhosted): add helm repo update command
diff: @@ -54,6 +54,8 @@ To install Gitpod in your Kubernetes cluster, follow these steps:
  ```bash
  helm repo add gitpod.io https://charts.gitpod.io
  + helm repo update
  +
  helm install -f values.custom.yaml gitpod gitpod.io/gitpod --version=0.10.0
  ```
  