Fix more missing backticks

Author: mdickinson

Doc/library/fractions.rst

@@ -199,8 +199,8 @@ another rational number, or from a string.
       :func:`format` built-in function, or :ref:`Formatted string literals
       <f-strings>`. The presentation types ``"e"``, ``"E"``, ``"f"``, ``"F"``,
       ``"g"``, ``"G"`` and ``"%"`` are supported. For these presentation types,
-      formatting for a :class:`Fraction` object `x` behaves as though the
-      object `x` were first converted to :class:`float` and then formatted
+      formatting for a :class:`Fraction` object ``x`` behaves as though the
+      object ``x`` were first converted to :class:`float` and then formatted
       using the float formatting rules, but avoids the loss of precision that
       might arise as a result of that conversion.