[Keyboard] Dumbo (#9656)

* added dumbo keyboard

* added my personal keymap

* changed picture in readme

* removed rev1 folder to reduce clutter and confusion

* missed a few changes in last commit, everything should be added now

* Apply suggestions from code review

Committed all of the suggested changes except for removing the bootloader reference comments in rules.mk as i think it is handy.

* Update keyboards/dumbo/rules.mk

Removed the bootloader reference as suggested

* Apply clean up of info.json

* Apply suggestions from noroadsleft to support community layout LAYOUT_SPLIT_3x6_4 in the future_4

keyboards/dumbo/rules.mk

@@ -0,0 +1,23 @@
+# MCU name
+MCU = atmega32u4
+
+# Bootloader selection
+BOOTLOADER = caterina
+
+# Build Options
+#   change yes to no to disable
+#
+BOOTMAGIC_ENABLE = no      # 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 = no           # USB Nkey Rollover
+BACKLIGHT_ENABLE = no      # Enable keyboard backlight functionality
+BLUETOOTH_ENABLE = no      # Enable Bluetooth
+AUDIO_ENABLE = no          # Audio output
+SPLIT_KEYBOARD = yes
+LTO_ENABLE = yes