Add dominoes exercise

[keiravillekode]

Each stone can be represented in a single byte: 4 bits for each half.

[[1, 2], [3, 1], [2, 3]] can become "\12\31\23"

We pass in dominoesOffset, dominoesCount

The result:

  ;; @returns {i32} 1 if can chain, 0 otherwise

instructions.append.md can mention that half a byte is known as a nibble