Return a list of points for a chevron shape comprised of two line segments intersecting at a right angle at the midpoint of s1, which can then be passed to pathFromPoints to draw the chevron.
s1
pathFromPoints
A line
Length of each line segment
List of points for chevron
Return a list of points for a chevron shape comprised of two line segments intersecting at a right angle at the midpoint of
s1, which can then be passed topathFromPointsto draw the chevron.