Added apk size badge to readme

README.md

@@ -2,5 +2,6 @@
 Android app for http://knigopis.com
 
 [![Build Status](https://travis-ci.org/sirekanyan/knigopis.svg?branch=master)](https://travis-ci.org/sirekanyan/knigopis)
+[![APK Size](https://img.shields.io/badge/dynamic/yaml.svg?label=apk%20size&url=https%3A%2F%2Fraw.githubusercontent.com%2Fsirekanyan%2Fknigopis%2Fmaster%2Fapp%2Fversion&query=%24.apkSize)](https://travis-ci.org/sirekanyan/knigopis)
 
 <a href='https://play.google.com/store/apps/details?id=com.sirekanyan.knigopis'><img alt='Get it on Google Play' src='https://play.google.com/intl/en_us/badges/images/generic/en_badge_web_generic.png'/></a>