The three insert iterators should each have an instantiation guide to initialize from a container.

Proposed change:

Add to the <iterator> header synopsis:

template <class Container>
back_insert_iterator(Container&) -> back_insert_iterator<Container>;
template <class Container>
front_insert_iterator(Container&) -> back_insert_iterator<Container>;
template <class Container>
insert_iterator(Container&, typename Container::iterator) -> insert_iterator<Container>;