title: How to publish pages on Github?
body: <p>Looks simple, I'm reading a lot about but I'm having issues to do it.</p>
  
  <pre><code>git add .
  git commit -m "documentation improvements"
  git push -u origin master
  git push -u origin gh-pages
  
  error: src refspec gh-pages does not match any.
  error: failed to push some refs to 'https://github.com/danielfpedro/simple-modal
  .git'
  </code></pre>
  
  <p>What I'm missing?</p>