Update scheduled-events.md

Add a note that it is possible for events to be cancelled

Author: adwilso

articles/virtual-machines/linux/scheduled-events.md

@@ -173,6 +173,8 @@ Each event is scheduled a minimum amount of time in the future based on the even
 | Preempt | 30 seconds |
 | Terminate | [User Configurable](../../virtual-machine-scale-sets/virtual-machine-scale-sets-terminate-notification.md#enable-terminate-notifications): 5 to 15 minutes |
 
+Once an event is scheduled it will move into the started state after it is either approved or the not before time passes. However in rare cases the operation will be cancelled by Azure before it starts. In that case the event will be removed from the Events array and the impact will not occur as previously scheduled. 
+	
 > [!NOTE] 
 > In some cases, Azure is able to predict host failure due to degraded hardware and will attempt to mitigate disruption to your service by scheduling a migration. Affected virtual machines will receive a scheduled event with a `NotBefore` that is typically a few days in the future. The actual time varies depending on the predicted failure risk assessment. Azure tries to give 7 days' advance notice when possible, but the actual time varies and might be smaller if the prediction is that there's a high chance of the hardware failing imminently. To minimize risk to your service in case the hardware fails before the system-initiated migration, we recommend that you self-redeploy your virtual machine as soon as possible.