Update csi-debug.md

Author: andyzhangx

docs/csi-debug.md

@@ -26,6 +26,11 @@ csi-smb-node-dr4s4                        3/3     Running   0          7m4s    1
  - get csi driver logs
 ```console
 $ kubectl logs csi-smb-node-cvgbs -c smb -n kube-system > csi-smb-node.log
+```
+
+ - check cifs mount inside driver
+```console
+kubectl exec -it csi-smb-node-cvgbs -n kube-system -c smb -- mount | grep cifs
 ```
 
 #### Update driver version quickly by editing driver deployment directly