Merge pull request #3205 from emqx/develop

README.md

@@ -74,7 +74,7 @@ The [EMQ X Roadmap uses Github milestones](https://github.com/emqx/emqx/mileston
 ## Community, discussion, contribution, and support
 
 You can reach the EMQ community and developers via the following channels:
-- [EMQX Slack](http://emqx.slack.com)
+- [EMQX Slack](https://slack-invite.emqx.io/)
 - [Twitter](https://twitter.com/emqtt)
 - [Forum](https://groups.google.com/d/forum/emqtt)
 - [Blog](https://medium.com/@emqtt)