[Azure AD roles] remove preview

Author: curtand

articles/active-directory/users-groups-roles/directory-assign-admin-roles.md

@@ -65,8 +65,6 @@ Users with this role can set or reset non-password credentials and can update pa
 * Message Center Reader
 * Reports Reader
 
-The Authentication administrator role is currently in public preview. This preview version is provided without a service level agreement, and it's not recommended for production workloads. Certain features might not be supported or might have constrained capabilities. For more information, see [Supplemental Terms of Use for Microsoft Azure Previews](https://azure.microsoft.com/support/legal/preview-supplemental-terms/).
-
 > [!IMPORTANT]
 > Users with this role can change credentials for people who may have access to sensitive or private information or critical configuration inside and outside of Azure Active Directory. Changing the credentials of a user may mean the ability to assume that user's identity and permissions. For example: