Updated supported devices

Author: jkasten2

README.md

@@ -19,13 +19,14 @@ See OneSignal's [Unity SDK API](https://documentation.onesignal.com/docs/unity-s
 See this repository's [release tags](https://github.com/OneSignal/OneSignal-Unity-SDK/releases) for a complete change log of every released version.
 
 #### Support
-Please visit this repository's [Github issue tracker](https://github.com/OneSignal/OneSignal-Unity-SDK/issues) for feature requests and bug reports related specificly to the SDK.
+Please visit this repository's [Github issue tracker](https://github.com/OneSignal/OneSignal-Unity-SDK/issues) for feature requests and bug reports related specifically to the SDK.
 
 For account issues and support please contact OneSignal support from the [OneSignal.com](https://onesignal.com) dashboard.
 
 #### Demo Project
 To make things easier, we have published a demo project in the `OneSignalExample/` folder of this repository.
 
 #### Supports:
-* iOS 7 - 12.2
-* Android 4.0.3 (API Level 15) through 9.0 (API Level 28), and derivatives such as Amazon ADM
+* iOS 9 - 14
+* Android 4.0.3 (API Level 15) - Android 11 (API Level 30)
+* Amazon FireOS 3 - 6