Exposure management - Update whats-new.md to add USX docset announcement

Author: cwatson-cat

exposure-management/whats-new.md

@@ -6,7 +6,7 @@ author: dlanger
 manager: rayne-wiselman
 ms.topic: overview
 ms.service: exposure-management
-ms.date: 11/18/2024
+ms.date: 12/03/2024
 
 ---
 
@@ -24,6 +24,12 @@ Learn more about MSEM by reading the blogs, [here](https://techcommunity.microso
 >
 > `https://aka.ms/msem/rss`
 
+## December 2024
+
+### New documentation library for Microsoft's unified security operations platform
+
+Find centralized documentation about [Microsoft's unified SecOps platform in the Microsoft Defender portal](/unified-secops-platform/overview-unified-security). Microsoft's unified SecOps platform brings together the full capabilities of Microsoft Sentinel, Microsoft Defender XDR, Microsoft Security Exposure Management, and generative AI into the Defender portal. Learn about the features and functionality available with Microsoft's unified SecOps platform, then start to plan your deployment.
+
 ## November 2024
 
 ### Announcing the General Availability of Microsoft Security Exposure Management