[span.cons] Fix indentation of remarks. (#2006)

Author: Eelis

source/containers.tex

@@ -10117,13 +10117,12 @@
 \tcode{size() == N \&\& data() == data(arr)}.
 
 \pnum
-\begin{remarks}
+\remarks
 These constructors shall not participate in overload resolution unless:
 \begin{itemize}
 \item \tcode{extent == dynamic_extent || N == extent} is \tcode{true}, and
 \item \tcode{remove_pointer_t<decltype(data(arr))>(*)[]} is convertible to \tcode{ElementType(*)[]}.
 \end{itemize}
-\end{remarks}
 \end{itemdescr}
 
 \indexlibrary{\idxcode{span}!constructor}%