Add clarifying TODO

aleksis/apps/alsijil/templates/alsijil/partials/register_coursebook.html

@@ -86,6 +86,7 @@
             {% endfor %}
           </td>
           <td class="lesson-te">
+            <!-- TODO: Why only with topic? Was already like this. But does it have to be with the new data-model?  -->
             {% if doc.topic %}
               {{ doc.get_teachers_short_names|join:', ' }}
             {% endif %}