[range.enumerate.overview] Add cross reference to [range.adaptor.object] (#6219)

Author: JohelEGP

source/ranges.tex

@@ -9483,7 +9483,7 @@
 
 \pnum
 \indexlibrarymember{enumerate}{views}%
-The name \tcode{views::enumerate} denotes a range adaptor object.
+The name \tcode{views::enumerate} denotes a range adaptor object\iref{range.adaptor.object}.
 Given a subexpression \tcode{E},
 the expression \tcode{views::enumerate(E)} is expression-equivalent to
 \tcode{enumerate_view<views::all_t<decltype((E))>>(E)}.