Add IT admin doc link

Author: FaithOmbongi

api-reference/beta/resources/applicationtemplate.md

@@ -72,6 +72,10 @@ The following JSON representation shows the resource type.
 }
 ```
 
+## Related content
+
+[Quickstart: Add an enterprise application from the Microsoft Entra gallery](/entra/identity/enterprise-apps/add-application-portal)
+
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