docs: Clean up.

Author: linbingquan

docs/api/zh/core/EventDispatcher.html

@@ -20,7 +20,7 @@ <h2>代码示例</h2>
 		<code>
 		// 为自定义对象添加事件
 
-		class Car extends EventDispatcher () {
+		class Car extends EventDispatcher {
 
 			start() {