[range.zip.transform.iterator] Avoid "defining" iterator_category

Use "determine"/"declare" instead.

Author: frederick-vs-ja

source/ranges.tex

@@ -11893,9 +11893,9 @@
 \pnum
 The member \grammarterm{typedef-name}
 \tcode{\exposid{iterator}::iterator_category}
-is defined if and only if \exposid{Base} models \libconcept{forward_range}.
+is declared if and only if \exposid{Base} models \libconcept{forward_range}.
 In that case,
-\tcode{\exposid{iterator}::iterator_category} is defined as follows:
+\tcode{\exposid{iterator}::iterator_category} is determined as follows:
 \begin{itemize}
 \item
 If