Add release badge

Author: ztombol

README.md

@@ -1,6 +1,7 @@
 # bats-assert
 
 [![GitHub license](https://img.shields.io/badge/license-CC0-blue.svg)](https://raw.githubusercontent.com/ztombol/bats-assert/master/LICENSE)
+[![GitHub release](https://img.shields.io/github/release/ztombol/bats-assert.svg)](https://github.com/ztombol/bats-assert/releases/latest)
 [![Build Status](https://travis-ci.org/ztombol/bats-assert.svg?branch=master)](https://travis-ci.org/ztombol/bats-assert)
 
 `bats-assert` is a helper library providing common assertions for