Update dataclasses.astuple and dataclasses.asdict docstrings to reflect that they deep copy objects in the field values, according to the changes in the docs, see python#26154

Author: ischurov

Lib/dataclasses.py

@@ -1284,7 +1284,7 @@ class C:
     If given, 'dict_factory' will be used instead of built-in dict.
     The function applies recursively to field values that are
     dataclass instances. This will also look into built-in containers:
-    tuples, lists, and dicts.
+    tuples, lists, and dicts. Other objects are copied with 'copy.deepcopy()'.
     """
     if not _is_dataclass_instance(obj):
         raise TypeError("asdict() should be called on dataclass instances")
@@ -1356,7 +1356,7 @@ class C:
     If given, 'tuple_factory' will be used instead of built-in tuple.
     The function applies recursively to field values that are
     dataclass instances. This will also look into built-in containers:
-    tuples, lists, and dicts.
+    tuples, lists, and dicts. Other objects are copied with 'copy.deepcopy()'.
     """
 
     if not _is_dataclass_instance(obj):