docs: Add badges

Author: medikoo

README.md

@@ -1,3 +1,6 @@
+[![Build status][build-image]][build-url]
+[![npm version][npm-image]][npm-url]
+
 # ext
 
 _(Previously known as `es5-ext`)_
@@ -36,3 +39,8 @@ npm install ext
   - [`includes`](docs/string_/includes.md)
 - `Thenable.prototype`
   - [`finally`](docs/thenable_/finally.md)
+
+[build-image]: https://github.com/medikoo/es5-ext/workflows/Integrate%20[ext]/badge.svg
+[build-url]: https://github.com/medikoo/es5-ext/actions?query=workflow%3AIntegrate%20[ext]
+[npm-image]: https://img.shields.io/npm/v/ext.svg
+[npm-url]: https://www.npmjs.com/package/ext