feat: add danmuku plugin documentation and i18n setup guide

- Created a new documentation file for the danmuku plugin with code examples for usage.
- Added a new i18n setup guide, detailing language settings, default languages, and how to import and modify languages.
- Included code snippets for initializing the Artplayer with different languages and examples for adding new languages.

docs/document/assets/start_i18n.md.BrnMiJ2K.lean.js

@@ -0,0 +1 @@
+import{_ as a,c as i,o as n,ak as l}from"./chunks/framework.xxfEszSJ.js";const c=JSON.parse('{"title":"语言设置","description":"","frontmatter":{},"headers":[],"relativePath":"start/i18n.md","filePath":"start/i18n.md","lastUpdated":1757137705000}'),p={name:"start/i18n.md"};function e(h,s,t,k,r,E){return n(),i("div",null,s[0]||(s[0]=[l("",14)]))}const g=a(p,[["render",e]]);export{c as __pageData,g as default};