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-ads.d.ts

@@ -48,5 +48,5 @@ declare const artplayerPluginAds: (option: Option) => (art: Artplayer) => Ads
 
 export default artplayerPluginAds
 
-export = artplayerPluginAds
-export as namespace artplayerPluginAds;
+export = artplayerPluginAds;
+export as namespace artplayerPluginAds;