Update 06.lens-level-down/.gitkeep, 07.lens-level-up/.gitkeep files

Deleted 01.curriculum/01.physics-chemistry-biology/03.Niv3/02.Geometrical-optics/05.paraxial-optics/02.paraxial-optics-simple-elements/03.lens/06.lens-transverse-1/.gitkeep, 01.curriculum/01.physics-chemistry-biology/03.Niv3/02.Geometrical-optics/05.paraxial-optics/02.paraxial-optics-simple-elements/03.lens/07.lens-transverse-2/.gitkeep files