Sync README from main

Signed-off-by: chenzhiguo <[email protected]>

README.md

@@ -13,6 +13,7 @@ Once Helm is set up properly, add the repository as follows:
 
 ```console
 helm repo add joylive https://jd-opensource.github.io/joylive-helm-charts
+helm repo update
 ```
 
 You can then run `helm search repo joylive` to see the charts.