add clarify and link for endpoint auth

Author: dem108

articles/machine-learning/how-to-troubleshoot-online-endpoints.md

@@ -786,7 +786,7 @@ The following table contains common error codes when consuming managed online en
 | Status code | Reason phrase             | Why this code might get returned                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
 | ----------- | ------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
 | 200         | OK                        | Your model executed successfully, within your latency bound.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
-| 401         | Unauthorized              | You don't have permission to do the requested action, such as score, or your token is expired.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
+| 401         | Unauthorized              | You don't have permission to do the requested action, such as score, or your token is expired or in the wrong format. For more information, see [endpoint authentication concept](concept-endpoints-online-auth.md) and [how to authenticate for endpoint](how-to-authenticate-online-endpoint.md).                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
 | 404         | Not found                 | The endpoint doesn't have any valid deployment with positive weight.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
 | 408         | Request timeout           | The model execution took longer than the timeout supplied in `request_timeout_ms` under `request_settings` of your model deployment config.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
 | 424         | Model Error               | If your model container returns a non-200 response, Azure returns a 424. Check the `Model Status Code` dimension under the `Requests Per Minute` metric on your endpoint's [Azure Monitor Metric Explorer](../azure-monitor/essentials/metrics-getting-started.md). Or check response headers `ms-azureml-model-error-statuscode` and `ms-azureml-model-error-reason` for more information. If 424 comes with liveness or readiness probe failing, consider adjusting [probe settings](reference-yaml-deployment-managed-online.md#probesettings) to allow longer time to probe liveness or readiness of the container. |