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

Use "declare" instead.

Author: frederick-vs-ja

source/ranges.tex

@@ -6668,7 +6668,7 @@
 \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 \exposid{ref-is-glvalue} is \tcode{true},
 \exposid{Base} models \libconcept{forward_range}, and
 \tcode{range_reference_t<\exposid{Base}>} models \libconcept{forward_range}.