Undocumented public function: Segment_Delaunay_graph_2::remove

[Yvee1]

I noticed that the public remove function of Segment_Delaunay_graph_2 is not documented (not present on https://doc.cgal.org), which may lead users to wrongly believe the function does not exist.

See: https://github.com/CGAL/cgal/blob/96f698ca09b61b6ca7587d43b022a0db43519699/Segment_Delaunay_graph_2/include/CGAL/Segment_Delaunay_graph_2.h#L1028-L1029 which is not present in the doc header: https://github.com/CGAL/cgal/blob/96f698ca09b61b6ca7587d43b022a0db43519699/Segment_Delaunay_graph_2/doc/Segment_Delaunay_graph_2/CGAL/Segment_Delaunay_graph_2.h#L671

EDIT: Also, on a related note, the documentation states that only insertions are supported (I'm assuming this is meant to mean in particular that deletions are not supported): https://github.com/CGAL/cgal/blob/96f698ca09b61b6ca7587d43b022a0db43519699/Segment_Delaunay_graph_2/doc/Segment_Delaunay_graph_2/CGAL/Segment_Delaunay_graph_2.h#L9 However, the remove function does exist and seems to work fine, so this comment is probably outdated and can be removed.