Remove new keyword from example, use final (#1076)

diff --git a/README.md b/README.md
index 3c94f85..e1c3f4d 100644
--- a/README.md
+++ b/README.md
@@ -113,7 +113,7 @@
 import 'package:dart_style/dart_style.dart';
 
 main() {
-  var formatter = new DartFormatter();
+  final formatter = DartFormatter();
 
   try {
     print(formatter.format("""