title: synchronize git branch with master, selectively
body: <p>I know how to <a href="https://stackoverflow.com/questions/5807459/github-mirroring-gh-pages-to-master">"synchronize" two branches</a> (i.e. the gh-pages branch is updated everytime the master is updated).</p>
  
  <p>What I would like is to sinchronize only a certain directory of master to the gh-pages branch. To be clear, that's what I would like to achieve:</p>
  
  <h2>master:</h2>
  
  <pre><code>+-- some
  |
  +-- file
  |
  +-- here
  |
  +-- dist/
      |
      +-- some_other
      |
      +-- dist_file
  </code></pre>
  
  <h2>gh-pages:</h2>
  
  <pre><code>+-- some_other
  |
  +-- dist_file
  </code></pre>
  
  <p>In other words, I'd like to have gh-pages updated as the dist/ directory of master every time master gets pushed.</p>
  
  <p>Is it feasible?</p>