add async functions to features

FEATURES.md

@@ -6,6 +6,16 @@
 [for (i of [1, 2, 3]) i * i]; // [1, 4, 9]
 ```
 
+## Async functions
+
+```javascript
+async function chainAnimationsAsync(elem, animations) {
+  for (var anim of animations) {
+    await anim(elem);
+  }
+}
+```
+
 ## Arrow functions
 
 ```javascript

README.md

@@ -55,6 +55,7 @@ It's as easy as:
 ## [Features](FEATURES.md)
 
  - [Array comprehension](FEATURES.md#array-comprehension)
+ - [Async functions](FEATURES.md#async-functions) via [regenerator](https://github.com/facebook/regenerator)
  - [Arrow functions](FEATURES.md#arrow-functions)
  - [Classes](FEATURES.md#classes)
  - [Computed property names](FEATURES.md#computed-property-names)