Add archive with all notation sheets

Signed-off-by: Emmy D'Anello <emmy.danello@animath.fr>

participation/models.py

@@ -567,6 +567,10 @@ class Pool(models.Model):
                     "They stay accessible to you. Only averages are given."),
     )
 
+    @property
+    def short_name(self):
+        return f"{self.get_letter_display()}{self.round}"
+
     @property
     def solutions(self):
         return [passage.defended_solution for passage in self.passages.all()]