Added licensing prerequisite (please review)

Added prerequisite to align with documentation: https://docs.microsoft.com/en-us/azure/active-directory/governance/entitlement-management-access-package-first#prerequisites
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cc: @msaburnley

Author: MarileeTurscak-MSFT

articles/active-directory/governance/entitlement-management-access-package-assignments.md

@@ -25,6 +25,13 @@ ms.collection: M365-identity-device-management
 
 In Azure AD entitlement management, you can see who has been assigned to access packages, their policy, and status. If an access package has an appropriate policy, you can also directly assign user to an access package. This article describes how to view, add, and remove assignments for access packages.
 
+## Prerequisites
+
+To use Azure AD entitlement management and assign users to access packages, you must have one of the following licenses:
+
+- Azure AD Premium P2
+- Enterprise Mobility + Security (EMS) E5 license
+
 ## View who has an assignment
 
 **Prerequisite role:** Global administrator, User administrator, Catalog owner, or Access package manager