chore: add note on required values in installation guide

Author: Steffen911

README.md

@@ -10,10 +10,13 @@ We provide a Helm chart that helps you deploy Langfuse on Kubernetes.
 
 ### Installation
 
+Configure the required secrets and parameters as defined below in a new `values.yaml` file.
+Then install the helm chart using the commands below:
+
 ```bash
 helm repo add langfuse https://langfuse.github.io/langfuse-k8s
 helm repo update
-helm install langfuse langfuse/langfuse
+helm install langfuse langfuse/langfuse -f values.yaml
 ```
 
 ### Upgrading