Allow {-y} in XYZ and clarify that the xyz rel type supports also TMS
Add a new vector-tile rel type that is pretty much aligned with XYZ, but allows specifically vector tiles. We'd then need to clarify that XYZ is raster.
Both points above may also be a first entry point for OGC API - Tiles (#12).
Clarify how XYZ relates to TMS and vector tiles.
We could for example:
xyzrel type supports also TMS