title: git submodule from local folder
body: <p>Have a git repo named <code>parent-repo</code>. It has folder <code>lib</code> with libraries. 'lib/one' is under control of <code>parent-repo</code>. And now I want to make git to recognize <code>lib/one</code> as git submodule of <code>parent-repo</code>.</p>
  
  <pre><code>cd lib/one
  git init
  git add .
  git commit -m 'first commit'
  </code></pre>
  
  <p>I think next steps are 0) <code>cd parent-repo</code>, 1) untrack <code>lib/one</code>, 2) register <code>lib/one</code> as submodule 3) stage and commit.<br>
  Please clear next steps with git commands if it is possible.</p>