message: Fixed logo size on readme
diff: <p align="center">
  - <img align="center" src="https://graviton.ml/assets/graviton-logo.png" width="250" height="50" style="marign-bottom:15px" />
  + <img align="center" src="https://graviton.ml/assets/graviton-logo.png" width="256" height="64.5" style="marign-bottom:15px" />
  <br>
  <a href="https://graviton.ml">graviton.ml</a>
  </p>
  