Update description of origin

Author: duongau

articles/frontdoor/origin.md

@@ -27,7 +27,7 @@ This article describes concepts about how to map your web application deployment
 
 ## Origin
 
-An origin refers to the application deployment that Azure Front Door retrieves contents from when caching isn't enabled or when a cache gets missed. Azure Front Door supports origins hosted in Azure and applications hosted in your on-premises datacenter or with another cloud provider. An origin shouldn't be confused with your database tier or storage tier. The origin should be viewed as the endpoint for your application backend. When you add an origin to an origin group in the Front Door configuration, you must also configure the following settings:
+An origin refers to the application deployment that Azure Front Door retrieves contents from. Azure Front Door supports origins hosted in Azure and applications hosted in your on-premises datacenter or with another cloud provider. An origin shouldn't be confused with your database tier or storage tier. The origin should be viewed as the endpoint for your application backend. When you add an origin to an origin group in the Front Door configuration, you must also configure the following settings:
 
 * **Origin type:** The type of resource you want to add. Front Door supports autodiscovery of your application backends from App Service, Cloud Service, or Storage. If you want a different resource in Azure or even a non-Azure backend, select **Custom host**.