Add IRC badge for convenience
JerryScript-DCO-1.0-Signed-off-by: Youngil Choi
[![Build Status](https://travis-ci.org/jerryscript-project/jerryscript.svg?branch=master)](https://travis-ci.org/jerryscript-project/jerryscript)
[![Coverity Scan Build Status](https://scan.coverity.com/projects/12127/badge.svg)](https://scan.coverity.com/projects/jerryscript-project)
[![FOSSA Status](https://app.fossa.io/api/projects/git%2Bhttps%3A%2F%2Fgithub.com%2Fjerryscript-project%2Fjerryscript.svg?type=shield)](https://app.fossa.io/projects/git%2Bhttps%3A%2F%2Fgithub.com%2Fjerryscript-project%2Fjerryscript?ref=badge_shield)
+[![IRC Channel](https://img.shields.io/badge/chat-on%20freenode-brightgreen.svg)](https://kiwiirc.com/client/irc.freenode.net/#jerryscript)
JerryScript is a lightweight JavaScript engine for resource-constrained devices such as microcontrollers. It can run on devices with less than 64 KB of RAM and less than 200 KB of flash memory.
