[optional.ref.ctor] Fix punctuation

Author: Andreas-Krug

source/utilities.tex

@@ -4683,9 +4683,9 @@
 \pnum
 \constraints
 \begin{itemize}
-\item \tcode{is_same_v<remove_cv_t<T>, optional<U>>} is \tcode{false}, and
-\item \tcode{is_same_v<T\&, U>} is \tcode{false}.
-\item \tcode{is_constructible_v<T\&, const U>} is \tcode{true},
+\item \tcode{is_same_v<remove_cv_t<T>, optional<U>>} is \tcode{false},
+\item \tcode{is_same_v<T\&, U>} is \tcode{false}, and
+\item \tcode{is_constructible_v<T\&, const U>} is \tcode{true}.
 \end{itemize}
 
 \pnum