Let sessions have description

Fixes #364

Author: hroncok

naucse/models.py

@@ -339,6 +339,7 @@ def __str__(self):
     title = DataProperty(info)
     slug = DataProperty(info)
     date = DataProperty(info, default=None)
+    description = DataProperty(info, default=None)
 
     def _time(self, key, default_time):
         if self.date and default_time:

naucse/templates/course.html

@@ -42,6 +42,7 @@ <h4>
                             <small>({{ session.date | format_date }})</small>
                         {% endif %}
                     </h4>
+                    {% if session.description %}{{ session.description | markdown }}{% endif %}
                     {{ material_list(session.materials) }}
                 </div>
                 {% endfor %}