[Keyboard] add MelGeek MJ61 (#10341)

* [Keyboard] Support MJ61 which is a 60% ANSI STD Hotswap RGB keyboard

* Update keyboards/melgeek/mj61/mj61.c

* Update keyboards/melgeek/mj61/mj61.c

* [Keyboard] MJ61 Add license header for files and the link for readme

* Update keyboards/melgeek/mj61/readme.md

* Update keyboards/melgeek/mj61/rev1/config.h

* Update keyboards/melgeek/mj61/rev1/rules.mk

* Update keyboards/melgeek/mj61/mj61.c

* Update keyboards/melgeek/mj61/mj61.c

keyboards/melgeek/mj61/rev1/rules.mk

@@ -0,0 +1,20 @@
+# MCU name
+MCU = STM32F303
+
+# Build Options
+#   change yes to no to disable
+#
+BOOTMAGIC_ENABLE = lite        # 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 = no          # Enable keyboard backlight functionality
+RGBLIGHT_ENABLE = no           # Enable keyboard RGB underglow
+BLUETOOTH_ENABLE = no          # Enable Bluetooth
+RGB_MATRIX_ENABLE = IS31FL3741 # Use RGB matrix
+NO_USB_STARTUP_CHECK = no      # Disable initialization only when usb is plugged in