Keyboard: Bpiphany Frosty Flake Refactor, Configurator support and readme cleanup (#4648)

* Frosty Flake: layout macro refactor

- frosty_flake.h updated to use #pragma once
- KEYMAP renamed to LAYOUT
- KEYMAP_TKL renamed to LAYOUT_tkl

* Frosty Flake: keymap refactor

- config.h files updated to #pragma once
- deleted deprecated build script rules from rules.mk
- keymap.c files:
  - #include QMK_KEYBOARD_H
  - updated layout macro name
  - white space changes for readability

* Frosty Flake: Configurator support

* Frosty Flake: readme cleanup

- Fixed Hardware Availability link (old link was 404)
- tiny grammar fix (colon missing on compile-and-flash instructions)

keyboards/bpiphany/frosty_flake/keymaps/default/rules.mk

@@ -1,5 +1,5 @@
 # Build Options
-#   change to "no" to disable the options, or define them in the Makefile in 
+#   change to "no" to disable the options, or define them in the Makefile in
 #   the appropriate keymap folder that will get included automatically
 #
 BOOTMAGIC_ENABLE = no       # Virtual DIP switch configuration(+1000)
@@ -13,9 +13,5 @@ MIDI_ENABLE = no            # MIDI controls
 AUDIO_ENABLE = no           # Audio output on port C6
 UNICODE_ENABLE = no         # Unicode
 BLUETOOTH_ENABLE = no       # Enable Bluetooth with the Adafruit EZ-Key HID
-RGBLIGHT_ENABLE = no        # Enable WS2812 RGB underlight. 
+RGBLIGHT_ENABLE = no        # Enable WS2812 RGB underlight.
 SLEEP_LED_ENABLE = no       # Breathing sleep LED during USB suspend
-
-ifndef QUANTUM_DIR
-	include ../../../../Makefile
-endif