Add 'cancelled throughout' field, to highlight in the search results whether a service is completely cancelled

schemas/api/trains/TrainByHeadcode.json

@@ -36,6 +36,12 @@
             "description": "The TOC operating the service",
             "minLength": 2,
             "maxLength": 2
+        },
+        "ct": {
+            "type": "boolean",
+            "title": "Cancelled Throughout",
+            "name": "Cancelled Throughout",
+            "description": "Whether the train is cancelled throughout"
         }
     }
 }