chore(contributing): remove slack link on v5 (#2939)

Author: jaredcbaum

versioned_docs/version-v5/contributing/how-to-contribute.md

@@ -12,7 +12,7 @@ Please see the [Contributor Code of Conduct](coc.md) for information on the rule
 
 ## Creating an Issue
 
-- If you have a question about using the framework, please ask on the [Ionic Forum](http://forum.ionicframework.com/) or in the [Ionic Worldwide Slack](https://ionicworldwide.herokuapp.com/) group.
+- If you have a question about using the framework, please ask on the [Ionic Forum](http://forum.ionicframework.com/).
 
 - It is required that you clearly describe the steps necessary to reproduce the issue you are running into. Although we would love to help our users as much as possible, diagnosing issues without clear reproduction steps is extremely time-consuming and simply not sustainable.