Fix command typo in unregister-register-machine.md

Corrected the command from 'Invoke-ArzStackHCiArcReset' to 'Invoke-AzStackHCiArcReset' for proper execution.

Author: joao-panao

azure-local/manage/unregister-register-machine.md

@@ -41,7 +41,7 @@ Before you begin, ensure you have the following:
 1. Unregister the machine. Run the following command:
 
    ```powershell
-   Invoke-ArzStackHCiArcReset -ArmAccessToken $ArmAccessToken -TenantId $TenantId 
+   Invoke-AzStackHCiArcReset -ArmAccessToken $ArmAccessToken -TenantId $TenantId 
    ```
 
    Here's a description of the parameters used in the command:
@@ -77,4 +77,4 @@ Before you begin, ensure you have the following:
 
 ## Next steps
 
-- Learn how to register Azure Local machines: [Register Azure Local machines](../deploy/deployment-without-azure-arc-gateway.md).
+- Learn how to register Azure Local machines: [Register Azure Local machines](../deploy/deployment-without-azure-arc-gateway.md).