Configurable schema file for OpenMapTiles

[wipfli]

I would like to share a configurable schema file for OpenMapTiles. Where is the best place to put it in this repository?

I found the shortbread.yml config file inspiring and thought that we could do something similar with openmaptile.yml...

https://github.com/onthegomap/planetiler/blob/main/planetiler-custommap/src/main/resources/samples/shortbread.yml

[wipfli]

There are only two layers at the moment, but we could maybe collaborate on it... onthegomap/planetiler#374