[range.concat.view] Add missing \exposid for tuple-transform (#6951)

Author: hewillk

source/ranges.tex

@@ -8710,7 +8710,7 @@
     using CT = @\exposid{make-unsigned-like-t}@<common_type_t<decltype(sizes)...>>;
     return (CT(sizes) + ...);
   },
-  tuple-transform(ranges::size, @\exposid{views_}@));
+  @\exposid{tuple-transform}@(ranges::size, @\exposid{views_}@));
 \end{codeblock}
 \end{itemdescr}