add async await example

Author: Liran

README.md

@@ -70,6 +70,12 @@ now *getAsync* is a promisified version of *client.get*:
 return getAsync('foo').then(function(res) {
     console.log(res); // => 'bar'
 });
+
+// or using [async await](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/async_function)
+async myFunc() {
+    const res = await getAsync('foo');
+    console.log(res);
+}
 ```
 
 #### Bluebird Promises