[move.sentinel] Remove extraneous "std" qualification in example (#5792)

Author: hewillk

source/iterators.tex

@@ -5253,13 +5253,12 @@
 \begin{example}
 A \tcode{move_if} algorithm is easily implemented with
 \tcode{copy_if} using \tcode{move_iterator} and \tcode{move_sentinel}:
-
 \begin{codeblock}
 template<@\libconcept{input_iterator}@ I, @\libconcept{sentinel_for}@<I> S, @\libconcept{weakly_incrementable}@ O,
          @\libconcept{indirect_unary_predicate}@<I> Pred>
   requires @\libconcept{indirectly_movable}@<I, O>
 void move_if(I first, S last, O out, Pred pred) {
-  std::ranges::copy_if(move_iterator<I>{first}, move_sentinel<S>{last}, out, pred);
+  ranges::copy_if(move_iterator<I>{first}, move_sentinel<S>{last}, out, pred);
 }
 \end{codeblock}
 \end{example}