Generate bin based plots in device documentation like tclarke's example

[mithro]

@tclarke has created a little utility which generates some nice plots for the different bins that various transistors are available in. See the fet01v8 example output at https://github.com/tclarke/sky130radio/tree/master/utils/gm_id_01v8 and below;

It would be nice if these where generated for all the fet devices ended up in the documentation at skywater-pdk.rtfd.io