added reference to the entra id auth concept page

Author: AikoBB

articles/communication-services/concepts/identity-model.md

@@ -174,6 +174,7 @@ The Microsoft Entra ID integration is currently in public preview and has the fo
 
 * To issue tokens, see [Create and manage access tokens for end users](../quickstarts/identity/access-tokens.md).
 * For an introduction to authentication, see [Authenticate to Azure Communication Services](./authentication.md).
+* For details on how authentication works in single-tenant and multitenant Microsoft Entra ID scenarios, refer to [Single-tenant and multitenant authentication for Microsoft Entra ID users](./entra-id-authentication-overview.md).
 * To read about data residency and privacy, see [Region availability and data residency](./privacy.md).
 * For a full sample of a simple identity management service, see [Trusted service tutorial](../tutorials/trusted-service-tutorial.md).
 * For a more advanced identity management sample which integrates with Entra ID and Microsoft Graph, see [Authentication service hero sample](../samples/trusted-auth-sample.md).