Update New-AzContainerGroup.md (#18309)

Author: BethanyZhou

src/ContainerInstance/help/New-AzContainerGroup.md

@@ -127,7 +127,7 @@ This commands creates a container group with a container instance, whose image i
 ### Example 7: Create a container group with system assigned and user assigned identity
 ```powershell
 $container = New-AzContainerInstanceObject -Name test-container -Image alpine
-$containerGroup = New-AzContainerGroup -ResourceGroupName test-rg -Name test-cg -Location eastus -Container $container -IdentityType "SystemAssigned, UserAssigned" -IdentityUserAssignedIdentity /subscriptions/<subscriptionId>/resourceGroups/<resourceGroup>/providers/Microsoft.ManagedIdentity/userAssignedIdentities/<UserIdentityName>
+$containerGroup = New-AzContainerGroup -ResourceGroupName test-rg -Name test-cg -Location eastus -Container $container -IdentityType "SystemAssigned, UserAssigned" -IdentityUserAssignedIdentity @{"/subscriptions/{subscriptionId}/resourceGroups/{resourceGroupName}/providers/Microsoft.ManagedIdentity/userAssignedIdentities/{identityName}" = @{}}
 ```
 
 ```output