Merge pull request #134896 from duongau/fdcustomhttps

Front Door: Custom HTTPS - note about cert

Author: PRMerger17

articles/frontdoor/front-door-custom-domain-https.md

@@ -10,7 +10,7 @@ ms.workload: infrastructure-services
 ms.tgt_pltfrm: na
 ms.devlang: na
 ms.topic: tutorial
-ms.date: 09/09/2020
+ms.date: 10/21/2020
 ms.author: duau
 # As a website owner, I want to enable HTTPS on the custom domain in my Front Door so that my users can use my custom domain to access their content securely.
 
@@ -131,6 +131,11 @@ Grant Azure Front Door permission to access the  certificates in your Azure Key
     - The key vault accounts for your subscription ID. 
     - The certificates (secrets) under the selected key vault. 
     - The available certificate versions. 
+
+> [!NOTE]
+> Leaving the certificate version as blank would lead to:
+> - The latest version of the certificate getting selected.
+> - Automatic rotation of certificates to the latest version, when a newer version of the certificate is available in your Key Vault.
  
 5. When you use your own certificate, domain validation is not required. Proceed to [Wait for propagation](#wait-for-propagation).