remove Slack use case from webhooks doc

Author: rosieyohannan

jekyll/_cci2/webhooks.md

@@ -25,7 +25,6 @@ Webhooks can be leveraged for various purposes. Some possible use cases for webh
 - Building a custom dashboard to visualize or analyze workflow/job events.
 - Sending data to incident management tools (such as Pagerduty).
 - Using tools like [Airtable]({{site.baseurl}}/2.0/webhooks-airtable) to capture data and visualize it.
-- Sending events to communication apps, such as Slack.
 - Alerting when a workflow is cancelled, then using the API to rerun the workflow.
 - Triggering internal notification systems to alert people when workflows/jobs complete.
 - Building your own automation plugins and tools.