docs: add license file

Author: afc163

LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2019-present react-component
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

@@ -178,7 +178,7 @@ The release flow is handled by `@rc-component/np` through the `rc-np` command af
 
 ## License
 
-@rc-component/menu is released under the [MIT](./LICENSE.md) license.
+@rc-component/menu is released under the [MIT](./LICENSE) license.
 
 [npm-image]: https://img.shields.io/npm/v/@rc-component/menu.svg?style=flat-square
 [npm-url]: https://npmjs.org/package/@rc-component/menu

README.zh-CN.md

@@ -178,7 +178,7 @@ npm run prepublishOnly
 
 ## 许可证
 
-@rc-component/menu 基于 [MIT](./LICENSE.md) 许可证发布。
+@rc-component/menu 基于 [MIT](./LICENSE) 许可证发布。
 
 [npm-image]: https://img.shields.io/npm/v/@rc-component/menu.svg?style=flat-square
 [npm-url]: https://npmjs.org/package/@rc-component/menu