Update README.md

README.md

@@ -9,7 +9,6 @@
 [![Translate Aldine](https://img.shields.io/badge/dynamic/json.svg?label=translated&url=https%3A%2F%2Ftenpercent.now.sh%2F%3Forganization%3Dpressbooks%26project%3Daldine&query=%24.status&colorB=e05d44&suffix=%25)](https://www.transifex.com/pressbooks/aldine/translate/)
 
 [![Packagist](https://img.shields.io/packagist/dt/pressbooks/pressbooks-aldine.svg)](https://packagist.org/packages/pressbooks/pressbooks-aldine)
-[![Slack](https://pressbooks-slack.now.sh/badge.svg)](https://pressbooks-slack.now.sh)
 [![Open Collective](https://opencollective.com/pressbooks/tiers/backer/badge.svg?label=backers&color=brightgreen)](https://opencollective.com/pressbooks/)
 [![Open Collective](https://opencollective.com/pressbooks/tiers/sponsor/badge.svg?label=sponsors&color=brightgreen)](https://opencollective.com/pressbooks/)
 **Tags:** publishing, catalog, pressbooks, default-theme