Remove reference to non-existing lessons-day-head-css-class

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

@@ -31,8 +31,7 @@
                 {% endif %}
               ">
           {% if forloop.first %}
-          <!-- TODO: There is no lessons-day-head class -->
-            <th rowspan="{{ documentations|length }}" class="lessons-day-head">{{ day|date:"D" }}</th>
+            <th rowspan="{{ documentations|length }}">{{ day|date:"D" }}</th>
           {% endif %}
           <td class="lesson-pe">
             {% if doc.amends %}