Update README.md (#85)

Updated the Slack link to our new community Discord link.

Author: heatherveva

README.md

@@ -153,6 +153,6 @@ npm run test
 
 # We want to hear from you.
 
-Come chat with us about open source in our community [Slack](https://www.bitovi.com/community/slack).
+Come chat with us about open source in our Bitovi community [Discord](https://discord.gg/J7ejFsZnJ4).
 
 See what we're up to by following us on [Twitter](https://twitter.com/bitovi).