Update Add-AzApplicationGatewayBackendAddressPool.md (#12321)

Fix Typo

Author: Antse

src/Network/Network/help/Add-AzApplicationGatewayBackendAddressPool.md

@@ -36,7 +36,7 @@ The first command gets the application gateway named ApplicationGateway01 in the
 ### Example 2: Add a back-end address pool by using backend server IP addresses
 ```
 PS C:\>$AppGw = Get-AzApplicationGateway -Name "ApplicationGateway01" -ResourceGroupName "ResourceGroup01"
-PS C:\> $AppGw = Add -AzApplicationGatewayBackendAddressPool -ApplicationGateway $ AppGw -Name "Pool02" -BackendIPAddresses "10.10.10.10", "10.10.10.11"
+PS C:\> $AppGw = Add-AzApplicationGatewayBackendAddressPool -ApplicationGateway $ AppGw -Name "Pool02" -BackendIPAddresses "10.10.10.10", "10.10.10.11"
 ```
 
 The first command gets the application gateway named ApplicationGateway01 in the resource group named ResourceGroup01, and stores it in the $AppGw variable.The second command adds the back-end address pool of the application gateway stored in $AppGw by using IP addresses.