message: add version badge
diff: <div align="center">
  <br />
  <br />
  + <a href="https://www.npmjs.com/package/@urql/preact">
  + <img alt="Npm version" src="https://badgen.net/npm/v/@urql/preact" />
  + </a>
  <a href="https://travis-ci.org/JoviDeCroock/preact-urql">
  <img alt="Test Status" src="https://api.travis-ci.org/JoviDeCroock/preact-urql.svg?branch=master" />
  </a>
  