Within your Compliance Rule Set, you can configure Monitoring
Rules.  One of the options is to monitor
for any OS version changes and generate alerts to admins.  This feature will allow you to watch for OS
upgrades that end users are preforming.

To setup this monitoring rule, click into a Rule Set and choose "Monitoring Rules" from the left menu

Once in this section, check the box next to "Monitor OS Version Changes"

You can then customize the Action to alert just the predefined Admin(s) or both the Admin(s) and the User.  You can also customize the message to be displayed in email here.