title: Create submodules from a already created bitbucket repo
body: <p>Hello I am using <code>git</code> and the web interface <code>bitbucket</code>
  I have the following structure in bitbucket</p>
  
  <pre><code>a
  |-b
  |-c
  </code></pre>
  
  <p>Thing is I want to be able to <code>clone</code> only <code>c</code>. I have red that <code>submodules</code> are the way to go.</p>
  
  <p>How can I make <code>c</code> a submodule and clone it somewhere else ?</p>