Merge pull request #189826 from JimacoMS4/fix-gh-86425-double-check-description-vs-actual-protocol

Update CleanSession and policy name for DPS MQTT

Author: PRMerger13

articles/iot-dps/iot-dps-mqtt-support.md

@@ -5,7 +5,7 @@ author: rajeevmv
 ms.service: iot-dps
 services: iot-dps
 ms.topic: conceptual
-ms.date: 10/16/2019
+ms.date: 02/25/2022
 ms.author: ravokkar
 ms.custom:  [amqp, mqtt]
 ---
@@ -44,7 +44,7 @@ If a device cannot use the device SDKs, it can still connect to the public devic
 * For the **Password** field, use a SAS token. The format of the SAS token is the same as for both the HTTPS and AMQP protocols:
 
   `SharedAccessSignature sr={URL-encoded-resourceURI}&sig={signature-string}&se={expiry}&skn=registration`
-  The resourceURI should be in the format `{idScope}/registrations/{registration_id}`. The policy name should be `registration`.
+  The resourceURI should be in the format `{idScope}/registrations/{registration_id}`. The policy name  (`skn`) is optional; if it's included, it should be set to `registration`.
 
   > [!NOTE]
   > If you use X.509 certificate authentication, SAS token passwords are not required.
@@ -53,7 +53,7 @@ If a device cannot use the device SDKs, it can still connect to the public devic
 
 The following is a list of DPS implementation-specific behaviors:
 
- * DPS does not support the functionality of **CleanSession** flag being set to **0**.
+ * DPS doesn't support persistent sessions. It treats every session as non-persistent, regardless of the value of the **CleanSession** flag.
 
  * When a device app subscribes to a topic with **QoS 2**, DPS grants maximum QoS level 1 in the **SUBACK** packet. After that, DPS delivers messages to the device using QoS 1.