chore(semantic-release): add semantic release badge

Author: mediumTaj

README.md

@@ -1,6 +1,7 @@
 # IBM Watson SDK for Unity
 [![Build Status](https://travis-ci.org/watson-developer-cloud/unity-sdk.svg?branch=develop)](https://travis-ci.org/watson-developer-cloud/unity-sdk)
 [![wdc-community.slack.com](https://wdc-slack-inviter.mybluemix.net/badge.svg)](http://wdc-slack-inviter.mybluemix.net/)
+[![semantic-release](https://img.shields.io/badge/%20%20%F0%9F%93%A6%F0%9F%9A%80-semantic--release-e10079.svg)](https://github.com/semantic-release/semantic-release)
 
 Use this SDK to build Watson-powered applications in Unity.