rtree with qbegin doesn't sort the elements by distance

Hi,
I just ran into an issue with the order of the returned values with an rtree using segments.

```
using Vector2d = boost::geometry::model::d2::point_xy ;
using seg2d = boost::geometry::model::segment ;
using rtree_seg = pair ;
boost::geometry::index::rtree > global_rtree_segs;
```
I had an issue with the result, so I decided to use an iterative query because it should have guaranteed sorted results from closest for farthest:

```
vector > results;
for ( auto it = global_rtree_segs.qbegin( boost::geometry::index::intersects( seg ) && boost::geometry::index::nearest( seg, 100 ) ); it != global_rtree_segs.qend(); ++it ){

results.push_back( *it );
}
```

and the distance check:
```
for ( u32 idx = -1; auto &e: r ){
idx += 1;
double d = boost::geometry::distance( seg, e.first );
std::cout << idx << " " << boost::geometry::wkt( e.first ) << ", distance= " << d << "\n";

}
```
And I saw that the distance are in random order.
But the Note at [https://www.boost.org/doc/libs/1_79_0/libs/geometry/doc/html/geometry/spatial_indexes/queries.html](url) says

> It's different in case of k-NN queries performed with query iterator returned by qbegin() function which guarantees the iteration over the closest Values first

So, right now, I want all the segments intersecting with a given segment, from closest to farthest, I need to implement a sort afterwards.

If I didn't get something, please tell me, otherwise, I think people should not rely on the note in the doc.