feat: add change log

Author: yaoleyaotouoO

docs/.vuepress/config.js

@@ -37,6 +37,10 @@ module.exports = {
         text: '主站',
         link: 'https://v2.formilyjs.org',
       },
+      {
+        text: 'CHANGELOG',
+        link: 'https://github.com/formilyjs/vant/blob/main/CHANGELOG.md',
+      },
       {
         text: 'GITHUB',
         link: 'https://github.com/formilyjs/vant',