Update danmuku.js file

docs/assets/example/danmuku.js

@@ -11,7 +11,7 @@ var art = new Artplayer({
     setting: true,
     plugins: [
         artplayerPluginDanmuku({
-            danmuku: 'https://d.artplayer.org?id=BV1ks411W7r5',
+            danmuku: '/assets/sample/danmuku.xml',
             speed: 5, // 弹幕持续时间，单位秒，范围在[1 ~ 10]
             opacity: 1, // 弹幕透明度，范围在[0 ~ 1]
             fontSize: 25, // 字体大小，支持数字和百分比