[Keyboard] Add swap hands support and readme update for Cradio (#15226)

Co-authored-by: filterpaper <filterpaper@localhost>

keyboards/cradio/cradio.c

@@ -2,6 +2,7 @@
  * ENDO Katsuhiro <ka2hiro@curlybracket.co.jp>
  * David Philip Barr <@davidphilipbarr>
  * Pierre Chevalier <pierrechevalier83@gmail.com>
+ * @filterpaper
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -18,3 +19,20 @@
  */
 
 #include "cradio.h"
+
+#ifdef SWAP_HANDS_ENABLE
+__attribute__ ((weak))
+const keypos_t PROGMEM hand_swap_config[MATRIX_ROWS][MATRIX_COLS] = {
+    // Left
+    {{4, 4}, {3, 4}, {2, 4}, {1, 4}, {0, 4}},
+    {{4, 5}, {3, 5}, {2, 5}, {1, 5}, {0, 5}},
+    {{4, 6}, {3, 6}, {2, 6}, {1, 6}, {0, 6}},
+    {{1, 7}, {0, 7}, {2, 7}, {3, 7}, {4, 7}},
+    // Right
+    {{4, 0}, {3, 0}, {2, 0}, {1, 0}, {0, 0}},
+    {{4, 1}, {3, 1}, {2, 1}, {1, 1}, {0, 1}},
+    {{4, 2}, {3, 2}, {2, 2}, {1, 2}, {0, 2}},
+    {{1, 3}, {0, 3}, {2, 3}, {3, 3}, {4, 3}}
+};
+#endif
+