Add antd-migration-helper to CHANGELOG

CHANGELOG.en-US.md

@@ -59,6 +59,8 @@ Learn more in the [Ant Design 3.0 announcement post](https://medium.com/ant-desi
 
 ### Breaking Changes
 
+We provide a [migration tool](https://github.com/ant-design/antd-migration-helper) to help you find depracated usages in your codebase.
+
 - Card's `noHovering` has been renamed to `hoverable`，and its default value now is `true`.
 - Added new Grid breakpoints. [#7230](https://github.com/ant-design/ant-design/pull/7230)
 - Form `getFieldDecorator`'s `exclusive` option has been removeed.

CHANGELOG.zh-CN.md

@@ -59,6 +59,8 @@ timeline: true
 
 ### 不兼容改动
 
+此版本有部分不兼容的改动，升级时确保修改相应的使用代码。另外由于人肉查找代码中的废弃用法过于低效，所以我们提供了 [antd-migration-helper](https://github.com/ant-design/antd-migration-helper) 用于扫描代码中的废弃用法。
+
 - Card 的 `noHovering` 属性重命名为 `hoverable`，且默认值改为 `true`。
 - 调整了 Grid 的响应式断点值。详见 [#7230](https://github.com/ant-design/ant-design/pull/7230)
 - Form `getFieldDecorator` 的 `exclusive` 参数被移除，此类场景应该由 Radio.Group、Checkbox.Group 之类的组件来完成。