README

These packages are copied from Dmitri Shuralyov's mtl packages and edited with Dmitri's permission:

• github.com/hajimehoshi/ebiten/v2/internal/graphicsdriver/metal/ca (copied from dmitri.shuralyov.com/gpu/mtl/example/movingtriangle/internal/ca)
• github.com/hajimehoshi/ebiten/v2/internal/graphicsdriver/metal/mtl (copied from dmitri.shuralyov.com/gpu/mtl)
• github.com/hajimehoshi/ebiten/v2/internal/graphicsdriver/metal/ns (copied from dmitri.shuralyov.com/gpu/mtl/example/movingtriangle/internal/ns)