feat: add danmuku plugin and i18n setup documentation

- Created a new documentation file for the danmuku plugin with code examples.
- Added a new documentation file for language settings (i18n) with detailed instructions on language imports, default languages, and how to add or modify languages.

docs/assets/ts/artplayer-plugin-dash-control.d.ts

@@ -13,5 +13,5 @@ declare const artplayerPluginDashControl: (option: { quality?: Config, audio?: C
 
 export default artplayerPluginDashControl
 
-export = artplayerPluginDashControl
-export as namespace artplayerPluginDashControl;
+export = artplayerPluginDashControl;
+export as namespace artplayerPluginDashControl;