(DOCSP-12478): Update dotnet compatibility table (#553)

Author: cbush

source/dotnet/compatibility.txt

@@ -26,12 +26,12 @@ version(s) you can use with {+service-short+} on your target platforms:
    * - Universal Windows Platform (UWP)
      - .NET Standard 2.0 or later (Fall Creators Update)
 
-   * - Android API level 10 or later
-     - Xamarin.Android for API level 10 or later
+   * - Android API level 16 or later
+     - Xamarin.Android for API level 16 or later
 
    * - macOS 10.11 or later
      - | .NET Core 2.0 or later
        | Xamarin.Mac for macOS 10.11 or later
 
-   * - iOS 7 or later
-     - Xamarin.iOS for iOS 7 or later
+   * - iOS 9 or later
+     - Xamarin.iOS for iOS 9 or later