Enhance signals documentation with additional context

Expanded the explanation of signals to include human-in-the-loop interventions.

Author: rmcdaniel

docs/features/signals.md

@@ -4,7 +4,7 @@ sidebar_position: 1
 
 # Signals
 
-Signals allow you to trigger events in a workflow from outside the workflow. This can be useful for reacting to external events or for signaling the completion of an external task.
+Signals allow you to trigger events in a workflow from outside the workflow. This can be useful for reacting to external events, enabling *human-in-the-loop* interventions, or for signaling the completion of an external task.
 
 To define a signal method on your workflow, use the `SignalMethod` annotation. The method will be called with any arguments provided when the signal is triggered: