Document how to convert from SIDPlay2 filter values

[MichaelHuth]

I measured the filters of two of my SID with A. Lanakilas method and have the coefficients that SIDPlay2 uses.

It is unclear how I calculate the values for the DeepSid filter settings panel from that.

The SIDPlay2 filter coefficients look like that:

[FilterEnigma6581R3_4885]
DistortionRate=0.50
DistortionPoint          =2048
VoiceNonlinearity        =0.96
DistortionCFThreshold    =2.5e-4
Type3BaseResistance      =1090649.9265298771
Type3Offset              =264401456.3944572
Type3Steepness           =1.0145069244334666
Type3MinimumFETResistance=19890.786352277173

[FilterEnigma6581R3_1585]
DistortionRate=0.50
DistortionPoint          =2048
VoiceNonlinearity        =0.96
DistortionCFThreshold    =2.5e-4
Type3BaseResistance      =1119380.8539989102
Type3Offset              =257709531.3343812
Type3Steepness           =1.0073881870085593
Type3MinimumFETResistance=20269.79137269368