title: How to update a fork on Github to upstream version without pumping everything though my local computer?
body: <p>Supposing I:</p>
  
  <ol>
  <li>Forked a 100 MB repository;</li>
  <li>Added just one little commit to it;</li>
  <li>After month, the upstream repositlry got a lot of commits and now 200 MB;</li>
  <li>Now I want to update my forked repository.</li>
  </ol>
  
  <p>I see two ways of doing it:</p>
  
  <ol>
  <li>Just push the updated version like usual. Drawback: it uploads 100 MB to network. Inefficient.</li>
  <li>Delete the forked repository entirely and re-fork it, then upload the changes. Drawback: hassle to set up things.</li>
  </ol>
  
  <p>How to do it efficiently?</p>