Fix missing code font

Fix decay-copy not in code font.

Author: steve-downey

papers/P2988/optional_range_optimization.tex

@@ -307,7 +307,7 @@ \chapter{Wording}
   then \tcode{E.base()}.
 \begin{addedblock}
 \item
-  Otherwise, if \tcode{E} is specialization of \tcode{optional} and \tcode{E} models \tcode{view}, then \placeholdernc{decay-copy}(E).
+  Otherwise, if \tcode{E} is specialization of \tcode{optional} and \tcode{E} models \tcode{view}, then \tcode{\placeholdernc{decay-copy}(E)}.
 \end{addedblock}
 \item
   Otherwise, if the type of \tcode{E} is \cv{} \tcode{subrange<reverse_iterator<I>, reverse_iterator<I>, K>}