added directory snapshot

README.md

@@ -102,6 +102,19 @@ await api.directory.list('/', async (remote_path, page_count, get_page) => {
   }
 });
 
+// Asynchronous directory list
+const snap = await api.directory.snapshot('/');
+try {
+  for (let i = 0; i < snap.page_count; i++) {
+    const items = await snap.get_page(i); // Always 'await'
+    console.log(items);
+  }
+} catch (err) {
+  console.log(err);
+} finally {
+  await snap.release();
+}
+
 // Create new directory
 await api.directory.create('/test');