Update README.md (#400)

README.md

@@ -290,7 +290,7 @@ Pull requests are welcome! See [CONTRIBUTING.md](CONTRIBUTING.md) for details.
 ## Support
 
 For general questions, check out the #planetiler channel on [OSM-US Slack](https://osmus.slack.com/) (get an
-invite [here](https://osmus-slack.herokuapp.com/)), or start
+invite [here](https://slack.openstreetmap.us/)), or start
 a [GitHub discussion](https://github.com/onthegomap/planetiler/discussions).
 
 Found a bug or have a feature request? Open a [GitHub issue](https://github.com/onthegomap/planetiler/issues) to report.