[Keyboard] add YMDK40 AIR40 (#19276)

Co-authored-by: jack <0x6a73@protonmail.com>
Co-authored-by: Drashna Jaelre <drashna@live.com>

keyboards/ymdk/ymd40/air40/rules.mk

@@ -0,0 +1,26 @@
+# MCU name
+MCU = atmega32u4
+
+# Bootloader selection
+BOOTLOADER = atmel-dfu
+
+# Build Options
+#   change yes to no to disable
+#
+BOOTMAGIC_ENABLE = yes      # Enable Bootmagic Lite
+MOUSEKEY_ENABLE = yes       # Mouse keys
+EXTRAKEY_ENABLE = yes       # Audio control and System control
+CONSOLE_ENABLE = no         # Console for debug
+COMMAND_ENABLE = no         # Commands for debug and configuration
+NKRO_ENABLE = no            # Enable N-Key Rollover
+BACKLIGHT_ENABLE = no      # Enable keyboard backlight functionality
+RGBLIGHT_ENABLE = no
+RGBLIGHT_SUPPORTED = no
+RGB_MATRIX_ENABLE = yes
+RGB_MATRIX_DRIVER = WS2812
+AUDIO_ENABLE = no           # Audio output
+AUDIO_SUPPORTED = no
+KEY_LOCK_ENABLE = no
+
+LAYOUTS = ortho_4x12
+