Update README.md

Author: yosuke-furukawa

README.md

@@ -1,7 +1,7 @@
 # [nodejs.jp][homepage]
 
 [![CircleCI](https://circleci.com/gh/nodejsjp/nodejsjp.github.com.svg?style=svg)](https://circleci.com/gh/nodejsjp/nodejsjp.github.com)
-[![](https://img.shields.io/badge/SLACK-JOIN_CHAT_%E2%86%92-551a8b.svg?style=flat-square)](https://iojs-jp-slack.herokuapp.com/)
+[![](https://img.shields.io/badge/SLACK-JOIN_CHAT_%E2%86%92-551a8b.svg?style=flat-square)](https://join.slack.com/t/jsconfjp/shared_invite/zt-1j7fqgvbq-Qa334TtwwKWC1eJBrgJ3yQ)
 
 # インストール
 ```sh