fix the invalid repo address (kubeflow#1291)

Signed-off-by: william-wang <[email protected]>

docs/volcano-integration.md

@@ -15,8 +15,8 @@ same environment, please refer [Quick Start Guide](https://github.com/volcano-sh
 
 Within the help of Helm chart, Kubernetes Operator for Apache Spark with Volcano can be easily installed with the command below:
 ```bash
-$ helm repo add incubator http://storage.googleapis.com/kubernetes-charts-incubator
-$ helm install incubator/sparkoperator --namespace spark-operator --set enableBatchScheduler=true --set enableWebhook=true
+$ helm repo add spark-operator https://googlecloudplatform.github.io/spark-on-k8s-operator
+$ helm install my-release spark-operator/spark-operator --namespace spark-operator --set enableBatchScheduler=true --set enableWebhook=true
 ```
 
 # Run Spark Application with Volcano scheduler