Linked NPM badge to NPM package page

Author: scriptcoded

README.md

@@ -1,6 +1,6 @@
 # simple-pdf
 
-![npm](https://img.shields.io/npm/v/simple-pdf)
+[![npm](https://img.shields.io/npm/v/simple-pdf)](https://www.npmjs.com/package/simple-pdf)
 
 `simple-pdf` aims to be a simple drop-in module for extracting text and images
 from PDF files. It exposes a promise-based and an event-based API.