Create migration-api-whats-new (SharePoint#7966)

* Create migration-api-whats-new

creation of new what's new file in response to ISV requests.

* fix date format

Co-authored-by: Andrew Connell <[email protected]>

Author: JoanneHendrickson

docs/apis/migration-api-whats-new

@@ -0,0 +1,21 @@
+---
+title: "Migration API What's new"
+ms.reviewer: jhendr
+author: JoanneHendrickson
+ms.author: jhendr
+manager: serdars
+ms.date: 05/17/2022
+audience: ITPro
+ms.topic: article
+ms.prod: sharepoint
+localization_priority: Priority
+ms.custom: admindeeplinkSPO
+description: "Learn about the new features and updates to the Migration API."
+---
+# What's new in the Migration API
+
+Check here to see what features or updates have been added to the Migration API. Here's a summary of what's included.  
+
+##  Fixes
+
+- **Changes to how Import API handles users**. As a response to issues arising from broken OneDrive scenarios when importing duplicate users, the API now blocks and detect duplicate user entries in UserGroup.xml. For details see: [Entering user identifiers in UserGroup.xml](/sharepoint/dev/apis/migration-api-overview#entering-user-identifiers-in-usergroup.xml)