Add docker hub badge

Author: everesio

README.md

@@ -2,7 +2,8 @@
 **Work in progress**
 
 [![Build Status](https://travis-ci.org/grepplabs/kafka-proxy.svg?branch=master)](https://travis-ci.org/grepplabs/kafka-proxy)
-
+[![Docker Hub](https://img.shields.io/badge/docker-latest-blue.svg)](https://hub.docker.com/r/grepplabs/kafka-proxy)
+[![Docker Pulls](https://img.shields.io/docker/pulls/grepplabs/kafka-proxy)](https://hub.docker.com/r/grepplabs/kafka-proxy)
 
 The Kafka Proxy is based on idea of [Cloud SQL Proxy](https://github.com/GoogleCloudPlatform/cloudsql-proxy). 
 It allows a service to connect to Kafka brokers without having to deal with SASL/PLAIN authentication and SSL certificates.