added example to dart packages

+import 'package:get_instance/get_instance.dart';
+
+void main() {
+  Get.put(Foo());
+
+  final foo = Get.find<Foo>();
+  final foo2 = Get.find<Foo>();
+  print(foo == foo2); // true
+}
+
+class Foo {}

+export 'package:get_core/get_core.dart';
 export 'src/bindings_interface.dart';
 export 'src/extension_instance.dart';
 export 'src/get_instance.dart';

+import 'package:get_rx/get_rx.dart';
+
+void main() {
+  var count = 0.obs;
+  ever(count, print);
+  count++;
+  count++;
+  count++;
+  count++;
+  count++;
+  count++;
+}