more details on options for AVR

- clearer description over the Arduino Bootloader and MiniCore bootloader options of AVR boards.

uCNC/src/hal/boards/avr/avr.ini

@@ -16,35 +16,38 @@ build_flags = ${env.build_flags} -std=gnu99 -Wall -fdata-sections -ffunction-sec
 lib_deps = ${env.lib_deps}
 ; lib_ignore = EEPROM, SPI, Wire
 
-[atmega328p]
+; If your board has Arduino original bootloader you should use this version
+; You can select the target board according to the list detailed in PlatformIO
+; https://docs.platformio.org/en/latest/frameworks/arduino.html#id3
+[avr-arduino]
 extends = common_avr
 board = uno
-;saves a bit of flash
-build_flags = ${common_avr.build_flags}
 
-[atmega328pb]
+; If your board has MiniCore (urboot) bootloader you should use this version
+; Note that you need to change the board to match one of the supporting microcontrollers by MiniCore
+; The supported list of microcontrollers is here https://github.com/MCUdude/MiniCore?tab=readme-ov-file#supported-microcontrollers
+[avr-minicore]
 extends = common_avr
-board = Atmega328PB
-;saves a bit of flash
+board = Atmega328P
+;use avrminicore 
 platform_packages=platformio/framework-arduino-avr-minicore@^3.0.0
-build_flags = ${common_avr.build_flags}
 
 [env:AVR-UNO]
-extends = atmega328p
-build_flags = ${atmega328p.build_flags} -D BOARD=\"src/hal/boards/avr/boardmap_uno.h\"
+extends = avr-arduino
+build_flags = ${common_avr.build_flags} -D BOARD=\"src/hal/boards/avr/boardmap_uno.h\"
 
 [env:AVR-CNC-Shield-V3]
-extends = atmega328p
-build_flags = ${atmega328p.build_flags} -D BOARD=\"src/hal/boards/avr/boardmap_uno_shield_v3.h\"
+extends = avr-arduino
+build_flags = ${common_avr.build_flags} -D BOARD=\"src/hal/boards/avr/boardmap_uno_shield_v3.h\"
 
 [env:AVR-X-Controller]
-extends = atmega328p
-build_flags = ${atmega328p.build_flags} -D BOARD=\"src/hal/boards/avr/boardmap_x_controller.h\"
+extends = avr-arduino
+build_flags = ${common_avr.build_flags} -D BOARD=\"src/hal/boards/avr/boardmap_x_controller.h\"
 
 [env:AVR-MKS-DLC]
-extends = atmega328p
+extends = avr-arduino
 board_build.f_cpu = 20000000UL
-build_flags = ${atmega328p.build_flags} -D BOARD=\"src/hal/boards/avr/boardmap_mks_dlc.h\"
+build_flags = ${common_avr.build_flags} -D BOARD=\"src/hal/boards/avr/boardmap_mks_dlc.h\"
 
 [env:AVR-MEGA2560-RAMPS-V1_4]
 extends = common_avr