Revert "Revert "Add top level readme, rename single_plate""

This reverts commit 95140cadf24150998e2d8bfc8d606cb4c10ad7e6.
Revert "Revert "reduced size to make holes line up with the single plate y-axis""

This reverts commit b4e11bc29a4aba2d82bc6a3b8662d0fa19c7b64b.