Update whats-new.md with anomalies removal news

Author: yelevin

articles/sentinel/whats-new.md

@@ -22,6 +22,7 @@ The listed features were released in the last three months. For information abou
 
 - [Unified security operations platform in the Microsoft Defender portal (preview)](#unified-security-operations-platform-in-the-microsoft-defender-portal-preview)
 - [Microsoft Sentinel now generally available (GA) in Azure China 21Vianet](#microsoft-sentinel-now-generally-available-ga-in-azure-china-21vianet)
+- [Two anomaly detections discontinued](#two-anomaly-detections-discontinued)
 
 ### Unified security operations platform in the Microsoft Defender portal (preview)
 
@@ -38,6 +39,14 @@ Microsoft Sentinel is now generally available (GA) in Azure China 21Vianet. Indi
 
 For more information, see also [Geographical availability and data residency in Microsoft Sentinel](geographical-availability-data-residency.md).
 
+### Two anomaly detections discontinued
+
+The following anomaly detections are discontinued as of March 26, 2024, due to low quality of results:
+- Domain Reputation Palo Alto anomaly
+- Multi-region logins in a single day via Palo Alto GlobalProtect
+
+For the complete list of anomaly detections, see the [anomalies reference page](anomalies-reference.md).
+
 ## March 2024
 
 - [SIEM migration experience now generally available (GA)](#siem-migration-experience-now-generally-available-ga)