[Keyboard] Add pluto12 (#15369)

Co-authored-by: Drashna Jaelre <drashna@live.com>
Co-authored-by: Ryan <fauxpark@gmail.com>

keyboards/psuieee/pluto12/pluto12.h

@@ -0,0 +1,24 @@
+// Copyright 2021 Will McGloughlin (@wymcg)
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include "quantum.h"
+
+/* This is a shortcut to help you visually see your layout.
+ *
+ * The first section contains all of the arguments representing the physical
+ * layout of the board and position of the keys.
+ *
+ * The second converts the arguments into a two-dimensional array which
+ * represents the switch matrix.
+ */
+#define LAYOUT( \
+    K00, K01, K02, K03, \
+    K10, K11, K12, K13, \
+    K20, K21, K22, K23 \
+) { \
+    {K00, K01, K02, K03}, \
+    {K10, K11, K12, K13}, \
+    {K20, K21, K22, K23} \
+}