Add badge signaling that types are available

Author: Pelle Wessman

README.md

@@ -1,6 +1,7 @@
 # @socketsecurity/sdk
 
 [![npm version](https://img.shields.io/npm/v/@socketsecurity/sdk.svg?style=flat)](https://www.npmjs.com/package/@socketsecurity/sdk)
+[![TypeScript types](https://img.shields.io/npm/types/@socketsecurity/sdk.svg?style=flat)](https://www.npmjs.com/package/@socketsecurity/sdk)
 [![js-standard-style](https://img.shields.io/badge/code%20style-standard-brightgreen.svg)](https://github.com/SocketDev/eslint-config)
 [![Follow @SocketSecurity](https://img.shields.io/twitter/follow/SocketSecurity?style=social)](https://twitter.com/SocketSecurity)