[android] updated changelog for 8.3.0-alpha.2 release (#15334)

Author: Langston Smith

platform/android/CHANGELOG.md

@@ -8,6 +8,12 @@ Mapbox welcomes participation and contributions from everyone.  If you'd like to
  - Fixed an issue where it was possible to set the map’s content insets then tilt the map enough to see the horizon, causing performance issues [#15195](https://github.com/mapbox/mapbox-gl-native/pull/15195)
  - Allow loading of a map without a Style URI or Style JSON [#15293](https://github.com/mapbox/mapbox-gl-native/pull/15293)
 
+## 8.3.0-alpha.2 - August 7, 2019
+[Changes](https://github.com/mapbox/mapbox-gl-native/compare/android-v8.3.0-alpha.1...android-v8.3.0-alpha.2) since [Mapbox Maps SDK for Android v8.3.0-alpha.1](https://github.com/mapbox/mapbox-gl-native/releases/tag/android-v8.3.0-alpha.1):
+
+### Bug fixes
+- Load a style without an URI or JSON [#15293](https://github.com/mapbox/mapbox-gl-native/pull/15293)
+
 ## 8.0.2 - July 31, 2019
 [Changes](https://github.com/mapbox/mapbox-gl-native/compare/android-v8.0.1...android-v8.0.2) since [Mapbox Maps SDK for Android v8.0.1](https://github.com/mapbox/mapbox-gl-native/releases/tag/android-v8.0.1):