[optional.assign] Use itemized list for operator=(U&& v) constraints (#7255)

Author: steve-downey

source/utilities.tex

@@ -3767,10 +3767,12 @@
 \begin{itemdescr}
 \pnum
 \constraints
-\tcode{is_same_v<remove_cvref_t<U>, optional>} is \tcode{false},
-\tcode{conjunction_v<is_scalar<T>, is_same<T, decay_t<U>>>} is \tcode{false},
-\tcode{is_constructible_v<T, U>} is \tcode{true}, and
-\tcode{is_assignable_v<T\&, U>} is \tcode{true}.
+\begin{itemize}
+\item \tcode{is_same_v<remove_cvref_t<U>, optional>} is \tcode{false},
+\item \tcode{conjunction_v<is_scalar<T>, is_same<T, decay_t<U>>>} is \tcode{false},
+\item \tcode{is_constructible_v<T, U>} is \tcode{true}, and
+\item \tcode{is_assignable_v<T\&, U>} is \tcode{true}.
+\end{itemize}
 
 \pnum
 \effects