Merge pull request ReactiveX#824 from ReactiveX/slack-channel-url

Update README.md

Author: kzaher

README.md

@@ -44,7 +44,7 @@ KVO observing, async operations and streams are all unified under [abstraction o
 
 ###### ... interact
 
-* All of this is great, but it would be nice to talk with other people using RxSwift and exchange experiences. <br />[![Slack channel](http://slack.rxswift.org/badge.svg)](http://slack.rxswift.org) [Join Slack Channel](http://slack.rxswift.org/)
+* All of this is great, but it would be nice to talk with other people using RxSwift and exchange experiences. <br />[![Slack channel](http://rxswift-slack.herokuapp.com/badge.svg)](http://slack.rxswift.org) [Join Slack Channel](http://rxswift-slack.herokuapp.com)
 * Report a problem using the library. [Open an Issue With Bug Template](ISSUE_TEMPLATE.md)
 * Request a new feature. [Open an Issue With Feature Request Template](Documentation/NewFeatureRequestTemplate.md)