docs(reference): update examples

example/helpers.dart

@@ -0,0 +1,16 @@
+import 'dart:io';
+import '../test/helpers/util.dart';
+
+Future<void> prepareRepo(String path) async {
+  if (await Directory(path).exists()) {
+    await Directory(path).delete(recursive: true);
+  }
+  await copyRepo(
+    from: Directory('test/assets/testrepo/'),
+    to: await Directory(path).create(),
+  );
+}
+
+Future<void> disposeRepo(String path) async {
+  await Directory(path).delete(recursive: true);
+}

example/reference_example.dart

@@ -1,18 +1,43 @@
 import 'dart:io';
 
 import 'package:libgit2dart/libgit2dart.dart';
+import 'helpers.dart';
 
-void main() {
-  final repo = Repository.open(Directory.current.path);
+void main() async {
+  // Preparing example repository.
+  final tmpDir = '${Directory.systemTemp.path}/example_repo/';
+  await prepareRepo(tmpDir);
 
+  final repo = Repository.open(tmpDir);
+
+  // Get list of repo's references.
   print('Repository references: ${repo.references.list()}');
 
+  // Get reference by name.
   final ref = repo.references['refs/heads/master'];
 
   print('Reference SHA hex: ${ref.target.sha}');
   print('Is reference a local branch: ${ref.isBranch}');
   print('Reference full name: ${ref.name}');
+  print('Reference shorthand name: ${ref.shorthand}');
 
+  // Create new reference (direct or symbolic).
+  final newRef = repo.createReference(
+    name: 'refs/tags/v1',
+    target: 'refs/heads/master',
+  );
+
+  // Rename reference.
+  newRef.rename('refs/tags/v1.1');
+
+  // Delete reference.
+  newRef.delete();
+
+  // free() should be called on object to free memory when done.
   ref.free();
+  newRef.free();
   repo.free();
+
+  // Removing example repository.
+  await disposeRepo(tmpDir);
 }