Upstream the KS spec into https://github.com/kaitai-io/kaitai_struct_formats

Hi. I see you have created a [Kaitai Struct spec](https://github.com/MelbourneSpaceProgram/Acrux1Tools/blob/master/Acrux1Payloads/Kaitai/acrux1beacon.ksy) for ACRUX format. Could you upstream it into https://github.com/kaitai-io/kaitai_struct_formats ?