Document load data calibration

[mhubii]

Ok, I will update the readme so that you can replicate as soon as I can. 👌

What do you mean by "the inverse dynamics model isn't perfect"? You mean that the FRI does not provide an accurate dynamics model?

Also, you mentioned that we should calibrate the load data, how can we achieve that? Do you mean by using the robot mastering button on the teach pendant? We do not have tools attached, but maybe we can try calibrating the sensors anyway.

Originally posted by @Hydran00 in #232 (comment)