If anything it would be:
By the way, the other attenuation parameters (constant and linear) are just for artistic purposes. Squared attenuation would be most correct, since the irradiance of a point light is:
E = max(0, cosAngle) * vLightIntensity / (squaredDistance);
For a diffuse surface the radiance then becomes:
L = E * vSurfaceColor / Pi;
You got it right, except for the division by Pi. (It is there for the energy conservation.)
The does not appear in the shader code though, as it cancels out with most BRDF's. For example lambert:
Whether needs to be in the shader code depends on the implementation. It depends on what his light is storing. It could either be radiance or radiant intensity. The way he is doing it now is storing radiant intensity, which is . Depending on whether his radiant intensity contains the multiplication by , the division by needs to be in the shader code or not.