website: add Traditional Chinese (#429)

Also README_TW added, hope it works :)

website/docs/.vitepress/locales/index.ts

@@ -1,6 +1,7 @@
 import { defineConfig } from 'vitepress'
 import en from './en'
 import zh_CN from './zh_CN'
+import zh_TW from './zh_TW'
 import vi_VN from './vi_VN'
 import id_ID from './id_ID'
 
@@ -18,6 +19,12 @@ export default defineConfig({
       themeConfig: zh_CN.themeConfig,
       description: zh_CN.description
     },
+    zh_TW: {
+      label: '繁體中文',
+      lang: zh_TW.lang,
+      themeConfig: zh_TW.themeConfig,
+      description: zh_TW.description
+    },
     vi_VN: {
       label: 'Tiếng Việt',
       lang: vi_VN.lang,