Update frozendict formatting

Author: hugovk

Doc/whatsnew/3.15.rst

@@ -192,9 +192,9 @@ raise :exc:`SyntaxError`).
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 A new :term:`immutable` type, :class:`frozendict`, is added to the :mod:`builtins` module.
-It does not allow modification after creation. A ``frozendict`` is not a subclass of ``dict``;
-it inherits directly from ``object``. A ``frozendict`` is :term:`hashable`
-as long as all of its keys and values are hashable. A ``frozendict`` preserves
+It does not allow modification after creation. A :class:`!frozendict` is not a subclass of ``dict``;
+it inherits directly from ``object``. A :class:`!frozendict` is :term:`hashable`
+as long as all of its keys and values are hashable. A :class:`!frozendict` preserves
 insertion order, but comparison does not take order into account.
 
 For example::