Update data-types.md adding stop_id to MDS Events

Signed-off-by: Matthew Marwedel <105882144+matthewmarwedel@users.noreply.github.com>

Author: matthewmarwedel

data-types.md

@@ -113,6 +113,7 @@ Events represent changes in vehicle status.
 | `battery_percent`       | Integer          | Required if Applicable | Percent battery charge of vehicle, expressed between 0 and 100 |
 | `fuel_percent`       | Integer          | Required if Applicable | Percent fuel in vehicle, expressed between 0 and 100 |
 | `trip_ids` | UUID[] | Required if Applicable | Trip UUIDs (foreign key to /trips endpoint), required if `event_types` contains `trip_start`, `trip_end`, `trip_cancel`, `trip_enter_jurisdiction`, or `trip_leave_jurisdiction` |
+| `stop_id`         | UUID            | Required if Applicable | Stop that the vehicle is currently located at. See [Stops][stops] |
 | `associated_ticket` | String | Optional | Identifier for an associated ticket inside an Agency-maintained 311 or CRM system |
 | `gtfs_stop_id` | UUID | Optional | A unique stop ID to be recorded when a vehicle makes a stop event at a location. Matches [GTFS](https://gtfs.org/documentation/schedule/reference/) `stop_id` |