AMJ40 Refactor (#11854)

* update keyboard source files

- add license headers (attributed to original keyboard submitter)
- #pragma once include guards
- file template matching
- readme update and template matching

* set sensible default keyboard settings

- enable Bootmagic Lite and Mouse Keys
- disable Console and Command
- remove default keymap's rules.mk file

* remove unnecessary files from default keymap

* refactor default keymap

* add additional layouts/keymaps

* update keyboard readme

- add images and bootloader instructions
- reformat link list

* convert tabs to spaces in default keymap

keyboards/amj40/rules.mk

@@ -2,27 +2,21 @@
 MCU = atmega32u4
 
 # Bootloader selection
-#   Teensy       halfkay
-#   Pro Micro    caterina
-#   Atmel DFU    atmel-dfu
-#   LUFA DFU     lufa-dfu
-#   QMK DFU      qmk-dfu
-#   ATmega32A    bootloadHID
-#   ATmega328P   USBasp
 BOOTLOADER = atmel-dfu
 
 # Build Options
-#   comment out to disable the options.
+#   change yes to no to disable
 #
-BOOTMAGIC_ENABLE = no  # Virtual DIP switch configuration
-MOUSEKEY_ENABLE  = no  # Mouse keys
-EXTRAKEY_ENABLE  = yes # Audio control and System control
-CONSOLE_ENABLE   = yes # Console for debug
-COMMAND_ENABLE   = yes # Commands for debug and configuration
-NKRO_ENABLE      = yes # USB Nkey Rollover - if this doesn't work, see here: https://github.com/tmk/tmk_keyboard/wiki/FAQ#nkro-doesnt-work
-RGBLIGHT_ENABLE  = yes # Enable keyboard underlight functionality
-BACKLIGHT_ENABLE = yes # Enable keyboard backlight functionality
-MIDI_ENABLE      = no  # MIDI controls
-AUDIO_ENABLE     = no
-UNICODE_ENABLE   = no  # Unicode
-BLUETOOTH_ENABLE = no  # Enable Bluetooth with the Adafruit EZ-Key HID
+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 = yes      # Enable keyboard backlight functionality
+RGBLIGHT_ENABLE = yes       # Enable keyboard RGB underglow
+BLUETOOTH_ENABLE = no       # Enable Bluetooth
+AUDIO_ENABLE = no           # Audio output