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.
- Included code snippets for initializing the Artplayer with different language settings.

docs/document/assets/en_start_i18n.md.Btgstn_9.lean.js

@@ -0,0 +1 @@
+import{_ as a,c as i,o as n,ak as l}from"./chunks/framework.xxfEszSJ.js";const g=JSON.parse('{"title":"Language Settings","description":"","frontmatter":{},"headers":[],"relativePath":"en/start/i18n.md","filePath":"en/start/i18n.md","lastUpdated":1772946913000}'),e={name:"en/start/i18n.md"};function p(t,s,h,r,k,E){return n(),i("div",null,s[0]||(s[0]=[l("",14)]))}const c=a(e,[["render",p]]);export{g as __pageData,c as default};