[Keyboard] Add MelGeek MJ6xy which is a 60% keyboard that support mul… (#13494)

Co-authored-by: Ryan <fauxpark@gmail.com>

keyboards/melgeek/mj6xy/rev3/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 = full      # Virtual DIP switch configuration
+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
+# Do not enable SLEEP_LED_ENABLE. it uses the same timer as BACKLIGHT_ENABLE
+SLEEP_LED_ENABLE = no        # Breathing sleep LED during USB suspend
+# if this doesn't work, see here: https://github.com/tmk/tmk_keyboard/wiki/FAQ#nkro-doesnt-work
+NKRO_ENABLE = yes            # USB Nkey Rollover
+BACKLIGHT_ENABLE = yes       # Enable keyboard backlight functionality
+RGBLIGHT_ENABLE = yes        # Enable keyboard RGB underglow
+BLUETOOTH_ENABLE = no        # Enable Bluetooth
+AUDIO_ENABLE = no            # Audio output
+BACKLIGHT_DRIVER = software
+
+LAYOUTS = 60_ansi
+