Split docs/rules/layers/table-c4b-layer-description.csv

[pkatarzynski]

Tweaks the /docs/rules/layers/table-c4b-layer-description.csv table and exports the notes appended to the CSV out of the table.

Fixes #144

[pkatarzynski]

I removed the \n strings from the source CSV as they appeared as redundant "n" characters in the RTD table see some descriptions in https://skywater-pdk.readthedocs.io/en/latest/rules/layers.html like areaid.hl{81:63} for instance

[mithro]

Doesn't https://github.com/google/skywater-pdk/pull/208 fix that?

[pkatarzynski]

The script https://github.com/google/skywater-pdk/blob/master/docs/rules/periphery/periphery-split-csv.py handles periphery rules kept in a separate RST and associated CSV files. The layer rules are defined in a CSV that is explicitly included in the RST. Would it be better to make the peripherly-split-csv.py more general and re-generate the remaining rule tables from CSVs using that script?

The other approach (which I followed) assumes cleaning the source CSVs.

[mithro]

Cleaning up the CSV file is fine, we just should clean up the CSV file by making the newlines work correctly?

[mithro]

Friendly ping!