Update mde-integration.md

Author: amirsc3

CloudAppSecurityDocs/mde-integration.md

@@ -18,6 +18,8 @@ This article describes the out-of-the-box integration available between Microsof
 
 - Microsoft Defender for Cloud Apps license
 
+- Devices must be onboarded to [Microsoft Defender for Endpoint](/microsoft-365/security/defender-endpoint/onboard-client)
+
 - One of the following:
 
     - Microsoft Defender for Endpoint with Plan 2