Merge branch 'delete-list-elements' into 'master'

arkindex/documents/api/elements.py

arkindex/documents/managers.py

arkindex/documents/tasks.py

arkindex/documents/tests/test_children_elements.py

arkindex/documents/tests/test_classes.py

arkindex/documents/tests/test_destroy_elements.py

arkindex/documents/tests/test_parents_elements.py

arkindex/project/openapi/patch.yml

arkindex/project/openapi/schemas.py

arkindex/project/tests/openapi/test_schemas.py

arkindex/project/triggers.py