feat: add danmuku plugin documentation and i18n setup guide

- Created a new documentation file for the danmuku plugin with code examples.
- Added a comprehensive guide for language settings, including default languages, importing languages, adding new languages, and modifying existing languages.
- Updated the i18n documentation to reflect changes in language handling and provide code snippets for implementation.

packages/artplayer-vitepress/docs/.vitepress/config.js

@@ -19,7 +19,7 @@ const config = {
       {
         text: '5.1.x',
         items: [
-          { text: 'Changelog', link: 'https://github.com/zhw2590582/ArtPlayer/blob/master/CHANGELOG_CN.md' },
+          { text: 'Changelog', link: 'https://github.com/zhw2590582/ArtPlayer/blob/master/CHANGELOG.md' },
           { text: 'Donation', link: 'https://github.com/zhw2590582/ArtPlayer#donations' },
           { text: 'Q群: 320881312', link: 'https://github.com/zhw2590582/ArtPlayer#qq-group' },
         ],