docs: add Vant 4 link (#10340)

packages/vant/docs/markdown/changelog.en-US.md

@@ -2,7 +2,10 @@
 
 ### Tips
 
-The current document is the changelog of Vant 3. If you want to view the changelog of Vant 2, please visit [Vant 2 Changelog](https://youzan.github.io/vant/v2/#/en-US/changelog).
+The current document is the changelog of Vant 3, other versions:
+
+- [Vant 2 Changelog](https://youzan.github.io/vant/v2/#/en-US/changelog)
+- [Vant 4 Changelog](https://youzan.github.io/vant/v4/#/en-US/changelog)
 
 ### Intro
 

packages/vant/docs/markdown/changelog.zh-CN.md

@@ -2,7 +2,10 @@
 
 ### 提示
 
-当前文档为 Vant 3 的更新日志，如需查询 Vant 2 的更新内容，请访问 [Vant 2 更新日志](https://youzan.github.io/vant/v2/#/zh-CN/changelog)。
+当前文档为 Vant 3 的更新日志，其他版本请参考：
+
+- [Vant 2 更新日志](https://youzan.github.io/vant/v2/#/zh-CN/changelog)
+- [Vant 4 更新日志](https://youzan.github.io/vant/v4/#/zh-CN/changelog)
 
 ### 介绍
 

packages/vant/vant.config.mjs

@@ -18,6 +18,7 @@ export default {
     versions: [
       { label: 'v1', link: '/vant/v1/' },
       { label: 'v2', link: '/vant/v2/' },
+      { label: 'v4', link: '/vant/v4/' },
     ],
     baiduAnalytics: {
       seed: 'ad6b5732c36321f2dafed737ac2da92f',