I would suggest reading the original alphago paper, it's extremely digestible, then skim the AlphaZero one, less detail there because it's a very similar architecture and actually it is simpler than the original. Think of AlphaZero as a scheme for improving the loss function, the actual architecture of the NN part is sort of unimportant, you can think of it as a black box, or maybe a black box with two smaller boxes sticking out of it.