(AzureCXP) fixes MicrosoftDocs/azure-docs-pr#550410

Clarified auto-purge behavior for orchestrations using ContinueAsNew by adding an explanatory note in the Purge behaviors section.

Author: pradeepmi-MSFT

articles/azure-functions/durable/durable-task-scheduler/durable-task-scheduler-auto-purge.md

@@ -21,6 +21,9 @@ Autopurge is an opt-in feature. You can enable it by defining retention policies
 
 The orchestration instances eligible for autopurge match those targeted by [the Durable SDK PurgeInstancesAsync API](/dotnet/api/microsoft.durabletask.client.durabletaskclientextensions.purgeinstancesasync?view=durabletask-dotnet-1.x&preserve-view=true).
 
+>[!Note]
+>Orchestrations that use ContinueAsNew may appear with a status that is marked as obsolete in some C# SDK versions. This is expected behavior. ContinueAsNew does not represent a terminal state. Instead, it restarts the orchestration with a new execution history while preserving the instance ID. Because of this, such instances are not considered completed or failed for auto-purge purposes and will not be removed until they eventually reach a true terminal state (Completed, Failed, or Terminated).
+
 Autopurge ignores orchestration data associated with non-terminal statuses. "Non-terminal" statuses indicate that the orchestration instance is either actively executing, paused, or in a state where it may resume in the future (waiting for external events or timers). These orchestrations that are continuing as new, where the current *execution* is completed, but a new instance has been started as a continuation.
 
 These statuses include: