Update cache-how-to-upgrade.md

Please refer this ICM for more information: https://portal.microsofticm.com/imp/v3/incidents/details/354095130/home

This is for scenarios where redis cache is having the private endpoint.

Author: vishalk9040

articles/azure-cache-for-redis/cache-how-to-upgrade.md

@@ -66,6 +66,12 @@ To upgrade a cache from 4 to 6 using the Azure CLI, use the following command:
 ```azurecli-interactive
 az redis update --name cacheName --resource-group resourceGroupName --set redisVersion=6
 ```
+>[!NOTE]
+> If private endpoint is enabled on the cache - based on whether PublicNetworkAccess is enabled or disabled,please refer the below commands:
+
+>If PublicNetworkAccess is enabled- az redis update --name cacheName --resource-group resourceGroupName --set publicNetworkAccess=Enabled redisVersion=6
+>If PublicNetworkAccess is disabled- az redis update --name cacheName --resource-group resourceGroupName --set publicNetworkAccess=Disabled redisVersion=6
+
 
 ## Upgrade using PowerShell