清理网页域名历史占位符

frontend/src/views/components/ConfigSettings/ConfigForm/ConfigForm.js

@@ -90,7 +90,7 @@ const validDomain = value => {
 const baseGroups = [
   group('site', '站点与域名', '', [
     field('domains.primary', '主邮件域名', 'text', { required: true, placeholder: 'example.com' }),
-    field('domains.web', '网页访问域名', 'text', { required: true, placeholder: 'mail.example.com' }),
+    field('domains.web', '网页访问域名', 'text', { required: true, placeholder: '请输入网页访问域名' }),
     field('domains.accepted', '接收邮件的域名', 'list', { required: true, wide: false, hint: '需包含主邮件域名，每个域名单独填写。', placeholder: 'example.com' }),
     field('logLevel', '日志级别', 'select', { options: options([['', '默认级别'], ['debug', '调试'], ['info', '信息'], ['warn', '警告'], ['error', '错误']]) })
   ]),