Hi I'm using Silverstripe CMS on the "Simple" template. I'm wondering how to create subtitles for the menu items.

The current navigation template is like so:

<nav class="primary">
<span class="nav-open-button">²</span>
<ul>
    <% loop $Menu(2) %>
        <li class="$LinkingMode"><a href="$Link" title="$Title.XML">$MenuTitle.XML</a></li>
    <% end_loop %>
</ul>

I'm thinking i could somehow edit $Menutitle.XML but how? Also the sub title should be displayed directly under the Title but as the same button. The SubTitle would need to have a different css rule so that it could be smaller. I know that the CMS has an area for me to edit the page titles which become the menu titles, would it be easy to add a subtitle to the admin like that or is there some other easier way? I only need to make a few of them.