docs: Add missing import to BlueapiClient docs (#1466)

Added missing `DataEvent` import to docs for BlueapiClient

Author: oliwenmandiamond

docs/tutorials/scripting-plans.md

@@ -160,6 +160,8 @@ This will be one of `WorkerEvent`, `ProgressEvent` or `DataEvent`.
 An example that prints data for each point could be something like
 
 ```python
+from blueapi.core.bluesky_types import DataEvent
+
 def feedback(evt):
     match evt:
         case DataEvent(name="start"):