Fix recovery command

Before fixing
========
Start-VMPublicIPUpgrade -RecoverFromFile ./AvSetPublicIPUpgrade_Recovery_2020-01-01-00-00.csv -AvailabilitySetName myAvSet -ResourceGroupName rg-myrg
========

After fixing
========
Start-AzAvSetPublicIPUpgrade -RecoverFromFile ./AvSetPublicIPUpgrade_Recovery_2020-01-01-00-00.csv -AvailabilitySetName myAvSet -ResourceGroupName rg-myrg
========

Author: atusi0628

articles/virtual-network/ip-services/public-ip-upgrade-availability-set.md

@@ -83,7 +83,7 @@ If a migration fails due to a transient issue, such as a network outage or clien
 To recover from a failed upgrade, pass the recovery log file path to the script with the `-recoverFromFile` parameter and identify the Availability Set to recover with the `-AvailabilitySetName` parameter, as shown in this example.
 
 ```powershell
-Start-VMPublicIPUpgrade -RecoverFromFile ./AvSetPublicIPUpgrade_Recovery_2020-01-01-00-00.csv -AvailabilitySetName myAvSet -ResourceGroupName rg-myrg
+Start-AzAvSetPublicIPUpgrade -RecoverFromFile ./AvSetPublicIPUpgrade_Recovery_2020-01-01-00-00.csv -AvailabilitySetName myAvSet -ResourceGroupName rg-myrg
 ```
 
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