title: Adding sub contextMenus in Google Chrome extension
body: <p>I can currently create a contextMenu (right-click menu) in a Google Chrome extension as follows:</p>
  
  <pre><code>chrome.contextMenus.create({
    title: "The name to click",
    contexts:["selection"],
    onclick: theFunctionToRun
  });
  </code></pre>
  
  <p>However, I would like to be able to add a contextMenu of submenus. I am implementing 10 tools that can be invoked through the right-click menu, but would like to have 2 menus each with 5 tools in them based on their categorization.</p>
  
  <p>I have not been able to find any info online or in documentation about this. I'm surprised other people do not want this feature as well so maybe I am just searching for the wrong thing. </p>
  
  <p>Is creating a contextMenu of submenus possible? If so, how can I do this?</p>