message: update logo path
diff: <p align="center">
  <a href="https://github.com/elitan/hasura-backend-plus">
  - <img src="logo.png" width="250px" alt="HBP" />
  + <img src="https://github.com/elitan/hasura-backend-plus/raw/master/logo.png" width="250px" alt="HBP" />
  </a>
  </p>
  