V5.1 Update tests and documentation

tests/api/test_v4_documents.py

@@ -206,6 +206,15 @@ def test_document_person_link_requires_role_id(tmp_path):
         )
 
     assert response.status_code == 422
+    payload = response.json()
+    assert "detail" in payload
+    assert isinstance(payload["detail"], list)
+    missing_role = [
+        item
+        for item in payload["detail"]
+        if isinstance(item, dict) and item.get("loc") == ["body", "role_id"] and item.get("type") == "missing"
+    ]
+    assert missing_role
 
 
 def test_duplicate_document_person_link_returns_conflict_envelope(tmp_path):