Update README.md

updated slack link

Author: Lyndon-prequel

README.md

@@ -2,7 +2,7 @@
 
 `preq` (prounounced "preek") is a free and open community-driven reliability problem detector
 
-[Documentation](https://docs.prequel.dev) | [Slack](https://prequel-dev.slack.com/) | [Playground](https://play.prequel.dev/) | [Mailing List](https://www.detect.sh)
+[Documentation](https://docs.prequel.dev) | [Slack](https://inviter.co/prequel) | [Playground](https://play.prequel.dev/) | [Mailing List](https://www.detect.sh)
 
 [![Unit Tests](https://github.com/prequel-dev/preq/actions/workflows/build.yml/badge.svg)](https://github.com/prequel-dev/preq/actions/workflows/build.yml)