Update articles/iot-edge/how-to-update-iot-edge.md

Co-authored-by: Damon Barry <[email protected]>

Author: PatAltimore

articles/iot-edge/how-to-update-iot-edge.md

@@ -92,7 +92,7 @@ Update IoT Edge:
 sudo apt-get install aziot-edge defender-iot-micro-agent-edge
 ```
 
-Running `apt-get install aziot-edge` upgrades the module runtime and installs the [identity service](https://azure.github.io/iot-identity-service/), `aziot-identity-service`, as a required dependency.
+Running `apt-get install aziot-edge` upgrades the security subsystem and installs the [identity service](https://azure.github.io/iot-identity-service/), `aziot-identity-service`, as a required dependency.
 
 It's recommended to install the micro agent with the Edge agent to enable security monitoring and hardening of your Edge devices. To learn more about Microsoft Defender for IoT, see [What is Microsoft Defender for IoT for device builders](../defender-for-iot/device-builders/overview.md).