message: Add contributor to README after merging side-effects PR
diff: <a href="https://github.com/niubsta"><img src="https://avatars0.githubusercontent.com/u/270320?s=122&v=4" title="niubsta" width="66" height="66" style="max-width:100%;"></a>
  <a href="https://github.com/allen-garvey"><img src="https://avatars1.githubusercontent.com/u/9314727?s=122s&v=4" title="allen-garvey" width="66" height="66" style="max-width:100%;"></a>
  <a href="https://github.com/sedlukha"><img src="https://avatars3.githubusercontent.com/u/14075940?s=122&v=4" title="sedlukha" width="66" height="66" style="max-width:100%;"></a>
  + <a href="https://github.com/wopian"><img src="https://avatars3.githubusercontent.com/u/3440094?s=122&v=4" title="wopian" width="66" height="66" style="max-width:100%;"></a>
  </p>
  </div>
  