📝 [#378] Fix api docs

Author: SilviaAmAm

backend/src/openarchiefbeheer/destruction/api/serializers.py

@@ -456,8 +456,9 @@ def create(self, validated_data: dict) -> DestructionListReview:
 class DestructionListItemReviewSerializer(serializers.ModelSerializer):
     zaak = serializers.SerializerMethodField(
         help_text=_(
-            "In the case that the zaak has already been deleted, only the URL field will be returned."
-        )
+            "In the case that the zaak has already been deleted, this field will be null."
+        ),
+        allow_null=True,
     )
 
     class Meta: