Add localized LED flash effect on keypress to Massdrop ALT (#4340)

keyboards/massdrop/alt/keymaps/reywood/rules.mk

@@ -0,0 +1,34 @@
+# project specific files
+SRC = led_programs.c
+SRC += matrix.c
+SRC += rgb_matrix_user.c
+
+#For platform and packs
+ARM_ATSAM = SAMD51J18A
+MCU = cortex-m4
+
+CUSTOM_MATRIX = yes
+
+# Build Options
+#   comment out to disable the options.
+#
+BOOTMAGIC_ENABLE = no       # Virtual DIP switch configuration(+1000)
+MOUSEKEY_ENABLE = no        # Mouse keys(+4700)
+EXTRAKEY_ENABLE = yes       # Audio control and System control(+450)
+CONSOLE_ENABLE = no         # Console for debug(+400)
+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 on B7 by default
+RGBLIGHT_ENABLE = no        # Enable keyboard RGB underglow
+MIDI_ENABLE = no            # MIDI support (+2400 to 4200, depending on config)
+UNICODE_ENABLE = no         # Unicode
+BLUETOOTH_ENABLE = no       # Enable Bluetooth with the Adafruit EZ-Key HID
+AUDIO_ENABLE = no           # Audio output on port C6
+FAUXCLICKY_ENABLE = no      # Use buzzer to emulate clicky switches
+HD44780_ENABLE = no         # Enable support for HD44780 based LCDs (+400)
+VIRTSER_ENABLE = no         # USB Serial Driver
+RAW_ENABLE = no             # Raw device
+AUTO_SHIFT_ENABLE = no      # Auto Shift