message: Update README.md
  added follow on Twitter button
diff: <a href="https://discord.gg/GXHk7ZfuG5">
  <img alt="chat on discord" src="https://img.shields.io/badge/chat-on%20discord-blueviolet"/>
  </a>
  + <a href="https://twitter.com/remultjs">
  + <img alt="Twitter Follow" src="https://img.shields.io/twitter/follow/remultjs?style=social">
  + </a>
  </div>
  ## What is Remult?
  