feat: add i18n support documentation and language import examples

- Created a new documentation file for language settings in i18n.
- Added examples for setting default languages and importing additional languages.
- Included instructions for adding and modifying languages in the ArtPlayer plugin.
- Introduced a new plugin: artplayer-plugin-liquid-glass with various build formats (legacy, mjs, etc.).

docs/assets/ts/artplayer-plugin-liquid-glass.d.ts

@@ -0,0 +1,16 @@
+interface Option {
+  'width': string
+  'max-width': string
+  'min-width': string
+}
+
+interface Result {
+  name: 'artplayerPluginLiquidGlass'
+}
+
+declare const artplayerPluginLiquidGlass: (option?: Option) => (art: Artplayer) => Result
+
+export default artplayerPluginLiquidGlass
+
+export = artplayerPluginLiquidGlass
+export as namespace artplayerPluginLiquidGlass;