docs: added docker pulls badge

README.md

@@ -6,6 +6,7 @@
 [![Sponsors on Open Collective](https://opencollective.com/wikijs/sponsors/badge.svg)](#sponsors)
 [![npm](https://img.shields.io/badge/npm-wiki.js-blue.svg?style=flat-square)](https://www.npmjs.com/package/wiki.js)
 [![Downloads](https://img.shields.io/github/downloads/Requarks/wiki/total.svg?style=flat-square)](https://www.npmjs.com/package/wiki.js)
+[![Docker Pulls](https://img.shields.io/docker/pulls/requarks/wiki.svg)](https://hub.docker.com/r/requarks/wiki/)  
 ![Build Status](https://requarks.visualstudio.com/_apis/public/build/definitions/5850c090-02b9-4312-b4ce-0e1f5677b574/6/badge)
 [![Codacy Badge](https://img.shields.io/codacy/grade/1d0217a3153c4595bdedb322263e55c8/master.svg?style=flat-square)](https://www.codacy.com/app/Requarks/wiki)
 [![Standard - JavaScript Style Guide](https://img.shields.io/badge/code%20style-standard-brightgreen.svg?style=flat-square)](http://standardjs.com/)