Fix Az.PrivateDNS Syntax Errors

Author: v-yuzhichen

src/PrivateDns/PrivateDns/help/Add-AzPrivateDnsRecordConfig.md

@@ -142,13 +142,13 @@ This example adds a CNAME record to an existing record set.
 
 ### Example 4: Add a MX record to a record set
 ```powershell
-$RecordSet = Get-AzPrivateDnsRecordSet -Name www -RecordType MX -ResourceGroupName MyResourceGroup -ZoneName myzone.com
+$RecordSet = Get-AzPrivateDnsRecordSet -Name @ -RecordType MX -ResourceGroupName MyResourceGroup -ZoneName myzone.com
 Add-AzPrivateDnsRecordConfig -Exchange mail.microsoft.com -Preference 5 -RecordSet $RecordSet
 Set-AzPrivateDnsRecordSet -RecordSet $RecordSet
 
 # You can also pipe the above sequence:
 
-Get-AzPrivateDnsRecordSet -Name www -RecordType MX -ResourceGroupName MyResourceGroup -ZoneName myzone.com | Add-AzPrivateDnsRecordConfig -Exchange mail.microsoft.com -Preference 5 | Set-AzPrivateDnsRecordSet
+Get-AzPrivateDnsRecordSet -Name "@" -RecordType MX -ResourceGroupName MyResourceGroup -ZoneName myzone.com | Add-AzPrivateDnsRecordConfig -Exchange mail.microsoft.com -Preference 5 | Set-AzPrivateDnsRecordSet
 ```
 
 ```output

src/PrivateDns/PrivateDns/help/Get-AzPrivateDnsRecordSet.md

@@ -55,7 +55,7 @@ The Get-AzPrivateDnsRecordSet cmdlet gets the Private Domain Name System (DNS) r
 
 ### Example 1: Get record sets with a specified name and type
 ```powershell
-$RecordSet = Get-AzPrivateDnsRecordSet -ResourceGroupName "MyResourceGroup" -ZoneName "myzone.com" -Name "www" -RecordType A
+Get-AzPrivateDnsRecordSet -ResourceGroupName "MyResourceGroup" -ZoneName "myzone.com" -Name "www" -RecordType A
 ```
 
 ```output
@@ -76,7 +76,7 @@ This command gets the record set of record type A named www in the specified res
 
 ### Example 2: Get record sets of a specified type
 ```powershell
-$RecordSets = Get-AzPrivateDnsRecordSet -ResourceGroupName "MyResourceGroup" -ZoneName "myzone.com" -RecordType A
+Get-AzPrivateDnsRecordSet -ResourceGroupName "MyResourceGroup" -ZoneName "myzone.com" -RecordType A
 ```
 
 ```output
@@ -109,7 +109,7 @@ This command gets an array of all record sets of record type A in the private zo
 
 ### Example 3: Get all record sets in a private zone
 ```powershell
-$RecordSets = Get-AzPrivateDnsRecordSet -ResourceGroupName "MyResourceGroup" -ZoneName "myzone.com"
+Get-AzPrivateDnsRecordSet -ResourceGroupName "MyResourceGroup" -ZoneName "myzone.com"
 ```
 
 ```output
@@ -143,7 +143,7 @@ This command gets an array of all record sets in the private zone named myzone.c
 ### Example 4: Get all record sets in a private zone, using a PSPrivateDnsZone object
 ```powershell
 $Zone = Get-AzPrivateDnsZone -Name "myzone.com" -ResourceGroupName "MyResourceGroup"
-$RecordSets = Get-AzPrivateDnsRecordSet -Zone $Zone
+Get-AzPrivateDnsRecordSet -Zone $Zone
 ```
 
 ```output