docs: Add link to Russian docs (vuejs#2012)

Author: Leronez

packages/docs/.vitepress/config/index.ts

@@ -11,5 +11,6 @@ export default defineConfig({
     zh: { label: '简体中文', lang: 'zh-CN', link: '/zh/', ...zhConfig },
     ko: { label: '한국어', lang: 'ko-KR', link: 'https://router.vuejs.kr/' },
     pt: { label: 'Português', lang: 'pt-PT', link: 'https://vue-router-docs-pt.netlify.app/' },
+    ru: { label: 'Русский', lang: 'ru-RU', link: 'https://vue-router-ru.netlify.app' },
   },
 })