feat(ui): add hidden bbox hotkey to alert

If you accidentally hit the hotkey and hide the bbox it could be
difficult to figure out how to un-hide it without the hotkey called out
in the alert.

Author: psychedelicious

invokeai/frontend/web/public/locales/en.json

@@ -2181,7 +2181,7 @@
             "rgAutoNegativeNotSupported": "Auto-Negative not supported for selected base model",
             "rgNoRegion": "no region drawn",
             "fluxFillIncompatibleWithControlLoRA": "Control LoRA is not compatible with FLUX Fill",
-            "bboxHidden": "Bounding box is hidden"
+            "bboxHidden": "Bounding box is hidden (shift+o to toggle)"
         },
         "errors": {
             "unableToFindImage": "Unable to find image",