edits per Chris and Mark review

Signed-off-by: Hannah Hunter <hannahhunter@microsoft.com>

daprdocs/content/en/developing-applications/building-blocks/workflow/workflow-features-concepts.md

@@ -63,6 +63,8 @@ You can use the following two techniques to write workflows that may need to sch
 
 1. **Use the _continue-as-new_ API**:  
     Each workflow SDK exposes a _continue-as-new_ API that workflows can invoke to restart themselves with a new input and history. The _continue-as-new_ API is especially ideal for implementing "eternal workflows", like monitoring agents, which would otherwise be implemented using a `while (true)`-like construct. Using _continue-as-new_ is a great way to keep the workflow history size small.
+
+    > The _continue-as-new_ API truncates the existing history, replacing it with a new history.
 
 1. **Use child workflows**:  
     Each workflow SDK exposes an API for creating child workflows. A child workflow behaves like any other workflow, except that it's scheduled by a parent workflow. Child workflows have:
@@ -149,16 +151,13 @@ Workflows can also wait for multiple external event signals of the same name, in
 
 Learn more about [external system interaction.]({{< ref "workflow-patterns.md#external-system-interaction" >}})
 
-## Limitations
-
-### Purging
+## Purging
 
-Workflow state can be purged from a state store, purging all its history and removing all metadata related to a specific workflow instance. The purge capability is typically used for workflows that have run to a `COMPLETED` or `TERMINATED` state. 
+Workflow state can be purged from a state store, purging all its history and removing all metadata related to a specific workflow instance. The purge capability is typically used for workflows that have run to a `COMPLETED`, `FAILED`, or `TERMINATED` state. 
 
-There are other times you may choose to purge a workflow history and reuse a workflow instance with new inputs, like: 
+Learn more in [the workflow API reference guide]({{< ref workflow_api.md >}}).
 
-- `CONTINUED_AS_NEW` state
-- A `FAILED` workflow instance
+## Limitations
 
 ### Workflow determinism and code restraints 
 

daprdocs/content/en/reference/api/workflow_api.md

@@ -174,6 +174,10 @@ Purge the workflow state from your state store with the workflow's instance ID.
 POST http://localhost:3500/v1.0-beta1/workflows/<workflowComponentName>/<instanceId>/purge
 ```
 
+{{% alert title="Note" color="primary" %}}
+Only `COMPLETED`, `FAILED`, or `TERMINATED` workflows can be purged.
+{{% /alert %}}
+
 ### URL parameters
 
 Parameter | Description