And also the rotation parameter. exRots. Appears to be the rotation angle (around Z from the original 2d object) for each point along the path.
So, the documentation, for those who are looking to know how to use this library (using path_extrude.scad), is as follows:
path_extrude(exShape=myPoints, exPath=myPath, exRots=, merge=false);`
Here's a working example that demonstrates all these parameters. Note that the shape is a pentagon with the top side elongated. The rotation list has the first element rotated 45 degrees so you can see which way positive numbers move the object.
myPoints = [
for(t = [0:72:359]) [((t==288) ? 3 : 1.5)*cos(t-18),((t==288) ? 3 : 1.5)*sin(t-18)]
myPath = [
for(a=[45:(360/12):360-45]) [10*cos(a), 10*sin(a), 0]
myRots = [
for(a=[0:len(myPath)-1]) (a==0) ? 45 : 0
path_extrude(exShape=myPoints, exPath=myPath, exRots=myRots, merge=false);