types(DatePicker): export DatePickerColumnType

packages/vant/src/date-picker/README.md

@@ -204,5 +204,5 @@ export default {
 The component exports the following type definitions:
 
 ```ts
-import type { DatePickerProps } from 'vant';
+import type { DatePickerProps, DatePickerColumnType } from 'vant';
 ```

packages/vant/src/date-picker/README.zh-CN.md

@@ -210,7 +210,7 @@ export default {
 组件导出以下类型定义：
 
 ```ts
-import type { DatePickerProps } from 'vant';
+import type { DatePickerProps, DatePickerColumnType } from 'vant';
 ```
 
 ## 常见问题

packages/vant/src/date-picker/index.ts

@@ -4,6 +4,7 @@ import _DatePicker, { DatePickerProps } from './DatePicker';
 export const DatePicker = withInstall(_DatePicker);
 export default DatePicker;
 export type { DatePickerProps };
+export type { DatePickerColumnType } from './DatePicker';
 
 declare module 'vue' {
   export interface GlobalComponents {