message: Add comma to README.md
  Add comma to README.md
diff: * Documentation: [Peercoin Docs](https://docs.peercoin.net)
  * Help:
  [Forum](https://talk.peercoin.net),
  -[Intro & Important Links](https://talk.peercoin.net/t/what-is-peercoin-intro-important-links/2889)
  +[Intro & Important Links](https://talk.peercoin.net/t/what-is-peercoin-intro-important-links/2889),
  [Telegram Chat](https://t.me/peercoin)
  Testing
  