Update whats-new.md

Author: batamig

defender-xdr/whats-new.md

@@ -21,6 +21,7 @@ Lists the new features and functionality in Microsoft Defender XDR.
 
 For more information on what's new with other Microsoft Defender security products and Microsoft Sentinel, see:
 
+- [What's new in Microsoft's unified security operations platform](/unified-secops-platform/whats-new)
 - [What's new in Microsoft Defender for Office 365](/defender-office-365/defender-for-office-365-whats-new)
 - [What's new in Microsoft Defender for Endpoint](/defender-endpoint/whats-new-in-microsoft-defender-endpoint)
 - [What's new in Microsoft Defender for Identity](/defender-for-identity/whats-new)