Added a note about global connection not automatically closing

shared/channels/src/channels/amqp_helpers.py

@@ -9,6 +9,8 @@ from workspaces.json import WorkflowEventSchema
 from workspaces.schema import WorkflowEvent
 
 T = TypeVar('T', contravariant=True)
+# Global connection; remains open until manually closed (I imagine by some sort of cleanup process)
+# FIXME: Does not currently automatically close itself
 CONN = None