Command is not correct (#12052)

* Command is not correct

We can use this command for secret not certificates because this command is not correct for certificates of KeyVault. When we use this command, the id will be below. I think this id is not correct for AppGW. 
https://xxxxx.vault.azure.net:443/certificates/xxxx/

The should be below. 

"KeyVaultSecretId": "https://xxxx.vault.azure.net:443/secrets/xxxx/"

When I used below command, I encountered error.

$secretId = $secret.Id.Replace($secret.Version, "")

"Set-AzApplicationGateway : SecretId 'https://xxxx.vault.azure.net:443/certificates/selftest/' specified in '/subscriptions/xxxxxxxxx/resourceGroups/apgw/p
roviders/Microsoft.Network/applicationGateways/AppGW/sslCertificates/SelfKeyCert' is invalid."

When I used below command, the operation was successful. So I think this document is not correct.

$secretId = $certificate.SecretId.Replace($certificate.Version, "")

* Command is not correct

This command is correct.

$secretId = $secret.SecretId.Replace($secret.Version, "")

* This command is correct.

I made a mistake. This is corrct.

Before
$secret.Id.Replace($secret.Version, "")

After
$secret.SecretId.Replace($secret.Version, "")

The Reason.

If we use below command, the URL will be "/certificates/" and it's invalid URL for AppGW.

 $secretId = $secret.Id.Replace($secret.Version, "")
> $secretId
https://testxxxx.vault.azure.net:443/certificates/testself/

So below command is correct.

$secretId = $secret.SecretId.Replace($secret.Version, "")
> $secretId
https://testxxxxxx.vault.azure.net:443/secrets/testself/

Author: ms-ishiyam

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

@@ -37,7 +37,7 @@ This command gets an application gateway named ApplicationGateway01 and then add
 ```
 PS C:\> $AppGW = Get-AzApplicationGateway -Name "ApplicationGateway01" -ResourceGroupName "ResourceGroup01"
 PS C:\> $secret = Get-AzKeyVaultCertificate -VaultName "keyvault01" -Name "sslCert01"
-PS C:\> $secretId = $secret.Id.Replace($secret.Version, "") # https://<keyvaultname>.vault.azure.net/secrets/
+PS C:\> $secretId = $secret.SecretId.Replace($secret.Version, "") # https://<keyvaultname>.vault.azure.net/secrets/
 PS C:\> $AppGW = Add-AzApplicationGatewaySslCertificate -ApplicationGateway $AppGW -Name "Cert01" -KeyVaultSecretId $secretId
 ```