Added TypeScript badge to README.md

Author: Claudéric Demers

README.md

@@ -9,6 +9,7 @@
 [![npm downloads](https://img.shields.io/npm/dm/react-tiny-virtual-list.svg)](https://www.npmjs.com/package/react-tiny-virtual-list)
 [![Build Status](https://travis-ci.org/clauderic/react-tiny-virtual-list.svg?branch=master)](https://travis-ci.org/clauderic/react-tiny-virtual-list)
 [![codecov](https://codecov.io/gh/clauderic/react-tiny-virtual-list/branch/master/graph/badge.svg)](https://codecov.io/gh/clauderic/react-tiny-virtual-list)
+![typescript](https://img.shields.io/badge/%3C%2F%3E-TypeScript-blue.svg)
 [![license](https://img.shields.io/github/license/mashape/apistatus.svg?maxAge=2592000)](https://github.com/clauderic/react-tiny-virtual-list/blob/master/LICENSE)
 [![Gitter](https://badges.gitter.im/clauderic/react-tiny-virtual-list.svg)](https://gitter.im/clauderic/react-tiny-virtual-list)