[range.concat.iterator] Avoid "defining" typedef-names

Use "declare" instead.

Author: frederick-vs-ja

source/ranges.tex

@@ -9078,7 +9078,7 @@
 \end{itemize}
 
 \pnum
-The member \grammarterm{typedef-name} \tcode{iterator_category} is defined
+The member \grammarterm{typedef-name} \tcode{iterator_category} is declared
 if and only if
 \tcode{\exposconcept{all-forward}<Const, Views...>} is modeled.
 In that case,