pytest: permanently enable doctest

pytest.ini

@@ -0,0 +1,2 @@
+[pytest]
+addopts = --doctest-modules

family_tree_yaml/yaml.py → yamily/yaml.py

@@ -2,7 +2,8 @@ import pathlib
 import typing
 
 import yaml
-from family_tree_yaml import Person
+
+from yamily import Person
 
 
 class _YamlLoader(yaml.SafeLoader):