feat: add danmuku plugin documentation and i18n setup instructions

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

docs/assets/ts/artplayer-plugin-libass.d.ts

@@ -1,10 +1,3 @@
-import type SubtitlesOctopus from '@hrgui/libass-wasm-ts'
-import type Artplayer from 'artplayer'
-import type { Options } from 'libass-wasm'
-
-export = artplayerPluginAss
-export as namespace artplayerPluginAss;
-
 declare const artplayerPluginAss: (options: Options) => (art: Artplayer) => {
   name: 'artplayerPluginLibass'
   libass: SubtitlesOctopus
@@ -15,3 +8,8 @@ declare const artplayerPluginAss: (options: Options) => (art: Artplayer) => {
   hide: () => void
   destroy: () => void
 }
+
+export default artplayerPluginAss
+
+export = artplayerPluginLibass;
+export as namespace artplayerPluginLibass;