Update URLs to django documn version

core/models/caves.py

@@ -161,7 +161,7 @@ class Cave(TroggleModel):
         # qms = self.qm_set.all().order_by('expoyear', 'block__date')
         qms = QM.objects.filter(cave=self).order_by(
             "expoyear", "block__date"
-        )  # a QuerySet, see https://docs.djangoproject.com/en/4.0/ref/models/querysets/#order-by
+        )  # a QuerySet, see https://docs.djangoproject.com/en/dev/ref/models/querysets/#order-by
         return qms  # a QuerySet
 
     def kat_area(self):