Added link to slack-ruby-bot-server-events.

Author: dblock

README.md

@@ -245,6 +245,7 @@ end
 
 A number of extensions use service manager callbacks and service timers to implement useful functionality.
 
+* [slack-ruby-bot-server-events](https://github.com/slack-ruby/slack-ruby-bot-server-events): Easily handle Slack slash commands, interactive buttons and events.
 * [slack-ruby-bot-server-mailchimp](https://github.com/slack-ruby/slack-ruby-bot-server-mailchimp): Subscribes new bot users to a Mailchimp mailing list.
 * [slack-ruby-bot-server-stripe](https://github.com/slack-ruby/slack-ruby-bot-server-stripe): Enables paid bots with trial periods and commerce through Stripe.