config/printer-creality-ender3-2018: add note about new boards

Signed-off-by: Luke Schwager <luke@blucobalt.dev>

config/printer-creality-ender3-2018.cfg

@@ -9,6 +9,13 @@
 # then one may need to flash a bootloader to the board - see the
 # Klipper docs/Bootloaders.md file for more information.
 
+# Some newer-stock Ender 3's may ship with 32-bit 4.2.2 (and/or 4.2.7?) boards. If your
+# printer has a 32-bit board, use ../printer-creality-ender3pro-2020.cfg. This config has all the correct
+# mappings, including for the {cr,bl}-touch. If you try/manage to flash an incompatible firmware, the
+# bootloader will still allow you to flash the correct version. You have not bricked your printer.
+
+# hint: if your host detects the printer as /dev/serial/by-id/usb-1a86_USB_Serial-if00-port0, you probably have a 32-bit board.
+
 # See docs/Config_Reference.md for a description of parameters.
 
 [stepper_x]