[Keyboard] Add keymap and settings for dactyl_manuform 6x6_5 thumb (#15526)

* Add dactyl manu 6x6 with stm32 support and 5thumb cluster

* Add review changes

* Add license to new files

* Fix enums for custom keymap

* Readme update

* Fix readme to follow one from template

* Add missing licence to files

* Update keyboards/handwired/dactyl_manuform/6x6/blackpill_f411/rules.mk

* Update keyboards/handwired/dactyl_manuform/6x6/blackpill_f411/rules.mk

* Remove readme from onekey keyboard

* Make separate macro for 5thumb

keyboards/handwired/dactyl_manuform/6x6/rules.mk

@@ -1,9 +1,3 @@
-# MCU name
-MCU = atmega32u4
-
-# Bootloader selection
-BOOTLOADER = caterina
-
 # Build Options
 #   change yes to no to disable
 #
@@ -17,3 +11,5 @@ BACKLIGHT_ENABLE = no       # Enable keyboard backlight functionality
 RGBLIGHT_ENABLE = no        # Enable keyboard RGB underglow
 AUDIO_ENABLE = no           # Audio output
 SPLIT_KEYBOARD = yes
+
+DEFAULT_FOLDER = handwired/dactyl_manuform/6x6/promicro