Update web-ui-dashboard.md

I rquest to update dashboard/v2.3.1 from v2.2.0

Refer to below 
https://github.com/kubernetes/dashboard

Author: sysnet4admin

content/en/docs/tasks/access-application-cluster/web-ui-dashboard.md

@@ -34,7 +34,7 @@ Dashboard also provides information on the state of Kubernetes resources in your
 The Dashboard UI is not deployed by default. To deploy it, run the following command:
 
 ```
-kubectl apply -f https://raw.githubusercontent.com/kubernetes/dashboard/v2.2.0/aio/deploy/recommended.yaml
+kubectl apply -f https://raw.githubusercontent.com/kubernetes/dashboard/v2.3.1/aio/deploy/recommended.yaml
 ```
 
 ## Accessing the Dashboard UI