Add UV_INDEX health data type to README

Author: iarata

packages/health/README.md

@@ -362,6 +362,7 @@ The plugin supports the following [`HealthDataType`](https://pub.dev/documentati
 | MENSTRUATION_FLOW            | NO_UNIT                 | yes              | yes                       |                                                                                                                                    |
 | WATER_TEMPERATURE            | DEGREE_CELSIUS          | yes              |                           | Related to/Requires Apple Watch Ultra's Underwater Diving Workout                                                                  |
 | UNDERWATER_DEPTH             | METER                   | yes              |                           | Related to/Requires Apple Watch Ultra's Underwater Diving Workout                                                                  |
+| UV_INDEX                     | COUNT                   | yes              |                           |                                                                                                                                    |
 | LEAN_BODY_MASS               | KILOGRAMS               | yes              | yes                       |                                                                                                                                    |
 
 ## Workout Types