Point to jupyter/jupyter gitter

README.md

 # docker-stacks
 
-[![Join the chat at https://gitter.im/jupyter/docker-stacks](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/jupyter/docker-stacks?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
+[![Join the chat at https://gitter.im/jupyter/jupyter](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/jupyter/jupyter?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
 
 Opinionated stacks of ready-to-run Jupyter applications in Docker.