Well, I felt bored, and I figured it out, so why not post it?
And, well, yeah. Enter this into Halo Waypoint and you get the left shoulder of the Raider armour set.
I think it's an interesting thing to do, even if the puzzle itself was freakishly easy. I'm curious to see what they do in the future. Hopefully, it will require more than Microsoft Paint.
Edit: It unlocks both shoulders.Read more >