Update Set-AzNotificationHubsNamespace.md (#15103)

Hi team,

Proposing to add the -SkuTier parameter to the examples, since the command fails with
"Set-AzNotificationHubsNamespace: The request content was invalid and could not be deserialized: Required property 'name' not found in 'sku'."
if it is not provided.

Author: tiantun

src/NotificationHubs/NotificationHubs/help/Set-AzNotificationHubsNamespace.md

@@ -35,17 +35,17 @@ To remove a critical namespace you must first remove the Critical tag.
 
 ### Example 1: Disable a namespace
 ```
-PS C:\>Set-AzNotificationHubsNamespace -Namespace "ContosoPartners" -Location "West US" -ResourceGroup "ContosoNotificationsGroup" -State "Disabled"
+PS C:\>Set-AzNotificationHubsNamespace -Namespace "ContosoPartners" -Location "West US" -ResourceGroup "ContosoNotificationsGroup" -State "Disabled" -SkuTier "Standard"
 ```
 
-This command disables the namespace named ContosoPartners located in the West US datacenter and assigned to the ContosoNotificationsGroup resource group.
+This command disables the Standard tier namespace named ContosoPartners located in the West US datacenter and assigned to the ContosoNotificationsGroup resource group.
 
 ### Example 2: Enable a namespace
 ```
-PS C:\>Set-AzNotificationHubsNamespace -Namespace "ContosoPartners" -Location "West US" -ResourceGroup "ContosoNotificationsGroup" -State "Active"
+PS C:\>Set-AzNotificationHubsNamespace -Namespace "ContosoPartners" -Location "West US" -ResourceGroup "ContosoNotificationsGroup" -State "Active" -SkuTier "Standard"
 ```
 
-This command enables the namespace named ContosoPartners located in the West US datacenter and assigned to the ContosoNotificationsGroup resource group.
+This command enables the Standard tier namespace named ContosoPartners located in the West US datacenter and assigned to the ContosoNotificationsGroup resource group.
 
 ## PARAMETERS