chore: export MenuRef type (#443)

Author: MadCcc

src/index.ts

@@ -4,6 +4,7 @@ import SubMenu, { SubMenuProps } from './SubMenu';
 import MenuItemGroup, { MenuItemGroupProps } from './MenuItemGroup';
 import { useFullPath as useOriginFullPath } from './context/PathContext';
 import Divider from './Divider';
+import { MenuRef } from './interface';
 
 /** @private Only used for antd internal. Do not use in your production. */
 const useFullPath = useOriginFullPath;
@@ -20,6 +21,7 @@ export {
   MenuItemProps,
   MenuItemGroupProps,
   useFullPath,
+  MenuRef,
 };
 
 type MenuType = typeof Menu & {