w_div_w_crit_roche update

[matthiasfabry]

While playing with very short period binaries using the single rotating star fp/ft corrections, I noticed the that the sigmoid function that is used to smooth very large j_rot was interpreted incorrectly. I fixed this in the documentation. I also cleaned up some obsolete ctrls, and took the liberty of updating the polynomial fits to the more accurate ones of Fabry+2022.

[evbauer]

@orlox could you give this one a quick review and merge when you're ready?