[Xamarin.Android.Tools.AndroidSdk] Add API-29, API-30 to KnownVersions (#89)

Author: jonathanpeppers

src/Xamarin.Android.Tools.AndroidSdk/AndroidVersions.cs

@@ -176,6 +176,12 @@ static bool MatchesId (AndroidVersion version, string id)
 newAndroidVersion(28,"9.0","Pie"){
 AlternateIds=new[]{"P"},
 },
+newAndroidVersion(29,"10.0","Android10"){
+AlternateIds=new[]{"Q"},
+},
+newAndroidVersion(30,"11.0"){
+AlternateIds=new[]{"R"},
+},
 };
 }