Fix Az.Maintenance Syntax Errors (#17651)

Author: v-yuzhichen

src/Maintenance/Maintenance/help/New-AzMaintenanceConfiguration.md

@@ -30,7 +30,7 @@ Create or Update configuration record
 
 ### Example 1
 ```powershell
-New-AzMaintenanceConfiguration -ResourceGroupName smdtest -Name workervmscentralus -MaintenanceScope Host -Location centralus -StartDateTime 2020-08-01 00:00 -ExpirationDateTime 2021-08-04 00:00 -TimeZone Pacific Standard Time -Duration 05:00 -RecurEvery Day
+New-AzMaintenanceConfiguration -ResourceGroupName smdtest -Name workervmscentralus -MaintenanceScope Host -Location centralus -StartDateTime "2020-08-01 00:00" -ExpirationDateTime "2021-08-04 00:00" -Timezone "Pacific Standard Time" -Duration 05:00 -RecurEvery Day
 ```
 
 ```output