Added missing entry to the What's new file

Updated the What's new file to contain the missing entry for PR microsoftgraph/microsoft-graph-docs#26089.

Author: JarbasHorst

concepts/whats-new-overview.md

@@ -21,7 +21,8 @@ For details about previous updates to Microsoft Graph, see [Microsoft Graph what
 
 ### Teamwork and communications | Messaging
 
-[Get](/graph/api/chatmessage-get#example-5-get-a-chat-message-with-an--for-everyone) a chat message with an @mention for everyone.
+- [Get](/graph/api/chatmessage-get#example-5-get-a-chat-message-with-an--for-everyone) a chat message with an @mention for everyone.
+- [Get](/graph/api/chatmessage-get#example-6-get-a-chat-message-with-a-forwarded-message) a chat message that has a forwarded message as an attachment.
 
 ## January 2025: New in preview only