Sidebar buttons as in the Demo using MarkDown

[faenuccio]

In the linked demo, there are three sidebar buttons, inserted as html

      <li><a href="https://github.com/orderedlist/minimal/zipball/master">Download <strong>ZIP File</strong></a></li>
      <li><a href="https://github.com/orderedlist/minimal/tarball/master">Download <strong>TAR Ball</strong></a></li>
      <li><a href="http://github.com/orderedlist/minimal">Fork On <strong>GitHub</strong></a></li>

Is it possible to add them (or equivalent ones with different urls) simply using the index.md file?