feat: add danmuku plugin documentation and i18n setup guide

- Created a new documentation file for the danmuku plugin with code examples.
- Added comprehensive language settings documentation, including default languages, import methods, and how to add or modify languages.
- Updated the i18n setup guide to reflect changes in language handling and provide code snippets for implementation.

test/types.plugin.test.ts

@@ -18,3 +18,7 @@ art.plugins.add(
     margin: [0, '10%'],
   }),
 )
+
+art.on('artplayerPluginDanmuku:load', () => {
+  //
+})