fixup: E formatting

Author: jensmaurer

source/expressions.tex

@@ -7632,7 +7632,7 @@
 with the first element of an object of type \tcode{T}, and
 \item
 the placement argument points to storage
-whose duration began within the evaluation of \tcode{E};
+whose duration began within the evaluation of $E$;
 \end{itemize}
 \end{itemize}