composition: Link to layers

[alixander]

The link keyword should accept a board as a value.

question: How does the cat go?

question.link: layers.cat

layers: {
  cat: {
    the cat -> meeeowwww: goes
  }
}

Which would then link it to whatever output path the cat layer gets output to. Result:

Kapture.2023-02-04.at.12.50.45.mp4