Update index.yml

Author: MicrosoftGuyJFlo

articles/active-directory/managed-identities-azure-resources/index.yml

@@ -8,7 +8,7 @@ metadata:
   description: Learn how to use managed identities for Azure resources in Azure AD.
   services: active-directory
   ms.service: active-directory
-  ms.subservice: devices
+  ms.subservice: msi
   ms.topic: landing-page
   author: barclayn
   ms.author: barclayn