Typo fix: Query string must be api-version, not a pi-version

Author: chgeuer

articles/virtual-machines/ephemeral-os-disks-deploy.md

@@ -132,7 +132,7 @@ You can reimage a Virtual Machine instance with ephemeral OS disk using REST API
 
 ```
 POST https://management.azure.com/subscriptions/{sub-
-id}/resourceGroups/{rgName}/providers/Microsoft.Compute/VirtualMachines/{vmName}/reimage?a pi-version=2019-12-01" 
+id}/resourceGroups/{rgName}/providers/Microsoft.Compute/VirtualMachines/{vmName}/reimage?api-version=2019-12-01" 
 ```
 
 ## PowerShell
@@ -151,4 +151,4 @@ Set-AzVmssStorageProfile -DiffDiskSetting Local -DiffDiskPlacement ResourceDisk
 ```
 
 ## Next steps
-For more information on [Ephemeral OS disk](ephemeral-os-disks.md).
+For more information on [Ephemeral OS disk](ephemeral-os-disks.md).