title: Iterate over markdown headers to create navigation menu
body: <p>I would like to make a single-large-page with a menu on the side that links directly to sections inside this single page. Similar to <a href="http://getbootstrap.com/components/" rel="noreferrer">the bootstrap manual</a> pages.</p>
  
  <p>I would like to write the page content in markdown. How can I make jekyll automatically create the navigation menu from the headers in the markdown page? I.e. loop/iterate over the headers to insert menu items?</p>