Tweak wording for dataclasses.replace (gh-117758)

Author: Gouvernathor

Doc/library/dataclasses.rst

@@ -430,8 +430,8 @@ Module contents
 
    Creates a new object of the same type as ``obj``, replacing
    fields with values from ``changes``.  If ``obj`` is not a Data
-   Class, raises :exc:`TypeError`.  If values in ``changes`` do not
-   specify fields, raises :exc:`TypeError`.
+   Class, raises :exc:`TypeError`.  If keys in ``changes`` are not
+   field names of the given dataclass, raises :exc:`TypeError`.
 
    The newly returned object is created by calling the :meth:`~object.__init__`
    method of the dataclass.  This ensures that