docs: update v5 migration doc for Message (#39097)

* docs: antd 5 deletes Message.warn

* docs: update v5 migration doc for Message

docs/react/migration-v5.en-US.md

@@ -117,6 +117,7 @@ This document will help you upgrade from antd `4.x` version to antd `5.x` versio
   - Static methods are no longer allowed to dynamically set `prefixCls` `maxCount` `top` `bottom` `getContainer` in `open`, Notification static methods will now have only one instance. If you need a different configuration, use `useNotification`.
   - `close` was renamed to `destroy` to be consistent with message.
 - Drawer `style` & `className` are migrated to Drawer panel node, the original properties are replaced by `rootClassName` and `rootStyle`.
+- The deprecated `message.warn` in 4.x is now completely removed, please use `message.warning` instead.
 
 #### Component refactoring and removal
 

docs/react/migration-v5.zh-CN.md

@@ -109,6 +109,7 @@ title: 从 v4 到 v5
   - 静态方法不再允许在 `open` 中动态设置 `prefixCls` `maxCount` `top` `bottom` `getContainer`，Notification 静态方法现在将只有一个实例。如果需要不同配置，请使用 `useNotification`。
   - `close` 改名为 `destroy`，和 message 保持一致。
 - Drawer `style` 和 `className` 迁移至 Drawer 弹层区域上，原属性替换为 `rootClassName` 和 `rootStyle`。
+- 4.x 中已经废弃的 `message.warn` 现在被彻底移除，请使用 `message.warning` 代替。
 
 #### 组件重构与移除