fix examples for new-azpolicyexemption (Azure#27220)

Author: VeryEarly

src/Resources/Policy.Autorest/docs/New-AzPolicyExemption.md

@@ -62,7 +62,7 @@ The final command exempts the policy assignment in $Assignment at the level of t
 ```powershell
 $VM = Get-AzVM -Name 'SpecialVM'
 $Assignment = Get-AzPolicyAssignment -Name 'VirtualMachinePolicyAssignment'
-New-AzPolicyExemption -Name 'VirtualMachinePolicyAssignment' -PolicyAssignment $Assignment -Scope $SpecialVM.Id -ExemptionCategory Waiver
+New-AzPolicyExemption -Name 'VirtualMachinePolicyAssignment' -PolicyAssignment $Assignment -Scope $VM.Id -ExemptionCategory Waiver
 ```
 
 The first command gets a VM named SpecialVM by using the Get-AzVM cmdlet and stores it in the $VM variable.

src/Resources/Policy.Autorest/examples/New-AzPolicyExemption.md

@@ -35,7 +35,7 @@ The final command exempts the policy assignment in $Assignment at the level of t
 ```powershell
 $VM = Get-AzVM -Name 'SpecialVM'
 $Assignment = Get-AzPolicyAssignment -Name 'VirtualMachinePolicyAssignment'
-New-AzPolicyExemption -Name 'VirtualMachinePolicyAssignment' -PolicyAssignment $Assignment -Scope $SpecialVM.Id -ExemptionCategory Waiver
+New-AzPolicyExemption -Name 'VirtualMachinePolicyAssignment' -PolicyAssignment $Assignment -Scope $VM.Id -ExemptionCategory Waiver
 ```
 
 The first command gets a VM named SpecialVM by using the Get-AzVM cmdlet and stores it in the $VM variable.