Update npm link in readme

Author: Tim Mendoza

README.md

@@ -1,6 +1,6 @@
 # @twilio-labs/plugin-rtc
 
-![npm](https://img.shields.io/npm/v/@twilio-labs/plugin-rtc)
+[![npm](https://img.shields.io/npm/v/@twilio-labs/plugin-rtc)](https://www.npmjs.com/package/@twilio-labs/plugin-rtc)
 [![CircleCI](https://circleci.com/gh/twilio-labs/plugin-rtc.svg?style=svg)](https://circleci.com/gh/twilio-labs/plugin-rtc)
 
 This plugin adds functionality to the [Twilio CLI](https://github.com/twilio/twilio-cli) which supports developing and deploying real-time communication apps.