Add missing Poland voivodeships

[gander]

Hi,

I'd like to contribute an update to the Poland voivodeships in this repository.

I'd like to:

• Add the missing 8 voivodeships to features/pl/ using boundaries sourced from geoBoundaries (CC BY 4.0)
• Add attribution to the existing features/pl/README.md as required by the geoBoundaries license

Would that be acceptable? Happy to open a PR if you're okay with the approach.

[gander]

@bhousel

[bhousel]

Sounds good!
I havent worked on the geofences myself, but some other contributors have written these:
https://github.com/osmlab/name-suggestion-index/wiki/Creating-and-Editing-Feature-Files
https://github.com/osmlab/name-suggestion-index/wiki/Regional-Features

As far as I know people use QGIS, which has features to keep the topology intact and close the seams between the borders of neighboring regions.