feat: add danmuku plugin documentation and i18n setup guide

- Created a new documentation file for the danmuku plugin with code examples.
- Added comprehensive i18n setup instructions, including default language settings, language imports, and examples for adding and modifying languages.
- Updated the structure and content of the i18n documentation to enhance clarity and usability.

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

@@ -16,7 +16,7 @@ const config = {
       { text: 'English Docs', link: '/en/', activeMatch: '/en/' },
       { text: 'Online Editor', link: 'https://artplayer.org' },
       {
-        text: '5.2.x',
+        text: '5.3.x',
         items: [
           { text: 'Changelog', link: 'https://github.com/zhw2590582/ArtPlayer/blob/master/CHANGELOG.md' },
           { text: 'Donation', link: 'https://github.com/zhw2590582/ArtPlayer#donations' },