fixed typo vd2 -> vd1
fixed typo vd2 -> vd1

Signed-off-by: Étienne Schmitt <25d5031dc1a1d443222aec9a4e916501ae23c255@inria.fr>

untereiner/CGoGN_2,david-cazier/CGoGN_2,etienneschmitt/CGoGN_2,david-cazier/CGoGN_2,cgogn/CGoGN_2,untereiner/CGoGN_2,cgogn/CGoGN_2