update API.md

Author: dalisoft

API.md

@@ -16,6 +16,7 @@ const {add, remove, isRunning, autoPlay} = TWEEN
     * [.Easing](#TWEEN.Easing) : <code>object</code>
     * [.Interpolation](#TWEEN.Interpolation) : <code>object</code>
     * [.Interpolator](#TWEEN.Interpolator) ⇒ <code>function</code>
+    * [.Timeline](#TWEEN.Timeline) : <code>object</code>
     * [.Tween](#TWEEN.Tween) : <code>object</code>
         * [.Tween#setMaxListener(count)](#TWEEN.Tween.Tween+setMaxListener)
         * [.Tween#on(event, callback)](#TWEEN.Tween.Tween+on)
@@ -93,6 +94,24 @@ Tween helper for plugins
 | a | <code>any</code> | Initial position |
 | b | <code>any</code> | End position |
 
+<a name="TWEEN.Timeline"></a>
+
+### TWEEN.Timeline : <code>object</code>
+Timeline main constructor.
+
+It works same as `Tween` instance, using `.repeat`, `.restart` or `etc` works like a `Tween`, so please see `Tween` class for methods
+
+**Kind**: static namespace of [<code>TWEEN</code>](#TWEEN)  
+**Extends**: <code>Tween</code>  
+
+| Param | Type | Description |
+| --- | --- | --- |
+| [params] | <code>Object</code> | Default params for new tweens |
+
+**Example**  
+```js
+let tl = new Timeline({delay:200})
+```
 <a name="TWEEN.Tween"></a>
 
 ### TWEEN.Tween : <code>object</code>