Add basic example (flutter#128)

Author: tvolkert

packages/file/CHANGELOG.md

@@ -1,3 +1,7 @@
+#### 5.0.10
+
+* Added example
+
 #### 5.0.9
 
 * Fix lints for project health

packages/file/example/main.dart

@@ -0,0 +1,14 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:file/file.dart';
+import 'package:file/memory.dart';
+
+Future<void> main() async {
+  final FileSystem fs = MemoryFileSystem();
+  final Directory tmp = await fs.systemTempDirectory.createTemp('example_');
+  final File outputFile = tmp.childFile('output');
+  await outputFile.writeAsString('Hello world!');
+  print(outputFile.readAsStringSync());
+}

packages/file/pubspec.yaml

@@ -1,5 +1,5 @@
 name: file
-version: 5.0.9
+version: 5.0.10
 authors:
 - Matan Lurey <matanl@google.com>
 - Yegor Jbanov <yjbanov@google.com>