title: How to add submodules within submodules
body: <p>I want to have submodules within my submodule. Adding the sub-submodule throws an error</p>
  
  <pre><code>(Parent)
  |
   --submodule--(Editor)
  |
   --submodule--(Editor)/(AndroidEditor)
  </code></pre>
  
  <p>I add them with commands:</p>
  
  <pre><code>git submodule add https://xx.git submodules/Editor/
  git submodule add -f https://yy.git submodules/Editor/AndroidEditor
  </code></pre>
  
  <p>And get the error adding the second submodule: </p>
  
  <blockquote>
    <p>fatal: Pathspec 'submodules/Editor/AndroidEditor' is in submodule
    'submodules/Editor' Failed to add submodule
    'submodules/Editor/AndroidEditor'</p>
  </blockquote>
  
  <p>Is the only way to add the sub-submodule from adding it to the <strong>Editor</strong> git repo and not to the <strong>Parent</strong> ?</p>