Update peps/pep-0814.rst

Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>

Author: vstinner

peps/pep-0814.rst

@@ -138,7 +138,7 @@ If some keys are in common, the values of the right operand are taken::
     >>> frozendict(x=1, y=2) | frozendict(y=5)
     frozendict({'x': 1, 'y': 5})
 
-The update operator `|=` does not modify a ``frozendict`` in-place, but
+The update operator ``|=`` does not modify a ``frozendict`` in-place, but
 creates a new ``frozendict``::
 
     >>> d = frozendict(x=1)