Updated README to reflect addition of Air Pollution wrapper methods.

README.md

@@ -83,9 +83,9 @@ code that uses data from [OpenWeathermap.org](https://openweathermap.org).
 - `OpenWeatherConnector` only supports the free, no-cost APIs provided by
   [OpenWeathermap.org](https://openweathermap.org). We do not have plans to
   support the subscription-based APIs.
-- As of this writing, `OpenWeatherConnector` only supports the *"weather"* data
-  set. We plan to add support for the *"onecall"*, *"forecast"*, and
-  *"air_pollution"* data sets.
+- As of this writing, `OpenWeatherConnector` only supports the *"weather"* and
+  *"air_pollution"* data sets. We plan to add support for the *"onecall"* and
+  *"forecast"* data sets.
 - We may add support for the
   [Geocoding API](https://openweathermap.org/api/geocoding-api) (*"direct"* and
   *"reverse"* data sets).