Add volume layers and controller to charybdis overlay

Author: barnacker

config/boards/shields/charybdis/charybdis_right.overlay

@@ -5,6 +5,7 @@
  */
 
 #include <input/processors.dtsi>
+#include <dt-bindings/zmk/hid.h>
 #include "charybdis.dtsi"
 
 &default_transform {
@@ -57,6 +58,7 @@
         spi-max-frequency = <2000000>;
         irq-gpios = <&gpio0 6 (GPIO_ACTIVE_LOW | GPIO_PULL_UP)>;
         scroll-layers = <3>;
+        volume-layers = <4>;
     };
 };
 
@@ -69,5 +71,9 @@
             layers = <3>;
             input-processors = <&zip_xy_to_scroll_mapper>;
         };
+        volume_controller {
+            layers = <4>;
+            sensor-bindings = <&inc_dec_kp C_VOL_UP C_VOL_DOWN>;
+        };
     };
 };