[const.iterators.types] Avoid "defining" iterator_category

Use "determine" and "declare" instead.

Author: frederick-vs-ja

source/iterators.tex

@@ -4359,7 +4359,7 @@
 \rSec3[const.iterators.types]{Member types}
 
 \pnum
-\tcode{basic_const_iterator<Iterator>::iterator_concept} is defined as follows:
+\tcode{basic_const_iterator<Iterator>::iterator_concept} is determined as follows:
 \begin{itemize}
 \item
 If \tcode{Iterator} models \libconcept{contiguous_iterator},
@@ -4378,7 +4378,7 @@
 \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{Iterator} models \libconcept{forward_iterator}.
 In that case,
 \tcode{basic_const_iterator<Iterator>::iterator_category} denotes