Add Polish scale

[Agilulfo]

Initial draft changes to add the polish scale a.k.a. kurtyka scale implements: #172

TODO:

• [x] Add polish scale to csv file
• [x] Update Readme
• [ ] Add polish scale implementation : src/scales/polish.ts
• [x] reference scale in : src/scales/index.ts
• [ ] Add tests
• [x] Generate json file
• [x] Document how to add a scale