Doc: Minor fixes (GH-23422)

Doc/library/stdtypes.rst

@@ -5065,7 +5065,7 @@ instantiated from the type::
 
       >>> class M(type):
       ...     def __or__(self, other):
-      ...     return "Hello"
+      ...         return "Hello"
       ...
       >>> class C(metaclass=M):
       ...     pass

Doc/whatsnew/3.10.rst

@@ -120,8 +120,8 @@ See :pep:`613` for more details.
 
 (Contributed by Mikhail Golubev in :issue:`41923`.)
 
-PEP604: New Type Union Operator
--------------------------------
+PEP 604: New Type Union Operator
+--------------------------------
 
 A new type union operator was introduced which enables the syntax ``X | Y``.
 This provides a cleaner way of expressing 'either type X or type Y' instead of