Add Changelog episode badge to README

Links to: https://changelog.com/204

README.md

@@ -1,6 +1,7 @@
 # IPFS - The Permanent Web
 
 [![ipfs](https://img.shields.io/badge/irc-%23ipfs-brightgreen.svg)](https://webchat.freenode.net/?channels=ipfs)
+[![Changelog #204](https://img.shields.io/badge/changelog-%23204-lightgrey.svg)](https://changelog.com/204)
 
 Welcome to IPFS! Why not [watch a video demo](https://www.youtube.com/watch?v=8CMxDNuuAiQ) to get started?