title: Git error: Changes not staged for commit
body: <p>I have my project + RestKit submodule. Error appeared when I changed RestKit settings. I added support armv6 and armv7 architecture. </p>
  
  <pre><code>git add .
  git add -u 
  git commit -m "new"
  # On branch master
  # Changes not staged for commit:
  #   (use "git add &lt;file&gt;..." to update what will be committed)
  #   (use "git checkout -- &lt;file&gt;..." to discard changes in working directory)
  #   (commit or discard the untracked or modified content in submodules)
  #
  #   modified:   RestKit (modified content)
  #
  </code></pre>
  
  <p>How to fix this error. </p>
  
  <p>UPDATE: I don't run git add RestKit.</p>
  
  <p>UPDATE2: The strusture of my project is:</p>
  
  <p><img src="https://i.stack.imgur.com/tRrM2.png" alt="enter image description here"></p>
  
  <p>I added submodule as </p>
  
  <pre><code>git submodule update -i
  </code></pre>