split out accuracy types

Author: marie-x

data-types.md

@@ -141,7 +141,8 @@ A standard point of vehicle telemetry. References to latitude and longitude impl
 | `altitude` | Double         | Required if Available | Altitude above mean sea level in meters                      |
 | `heading`  | Double         | Required if Available | Degrees - clockwise starting at 0 degrees at true North      |
 | `speed`    | Float          | Required if Available | Estimated speed in meters / sec as reported by the GPS chipset |
-| `accuracy` | Float          | Required if Available | Horizontal accuracy, in meters                               |
+| `horizontal_accuracy` | Float          | Required if Available | Horizontal accuracy, in meters                               |
+| `vertical_accuracy` | Float          | Required if Available | Horizontal accuracy, in meters                               |
 | `hdop`     | Float          | Required if Available | Horizontal GPS or GNSS accuracy value (see [hdop][hdop])     |
 | `satellites` | Integer      | Required if Available | Number of GPS or GNSS satellites                             |