docs: Clarify configuration settings for Ender 5 Pro

Signed-off-by: Benjie Gillam <[email protected]>

Author: benjie

config/printer-creality-ender5pro-2020.cfg

@@ -1,7 +1,7 @@
 # This file contains pin mappings for the stock 2020 Creality Ender 5
 # Pro with the 32-bit Creality 4.2.2 board. To use this config, during
 # "make menuconfig" select the STM32F103 with a "28KiB bootloader" and
-# with "Use USB for communication" disabled.
+# communication interface set to "Serial (on USART1 PA10/PA9)".
 
 # If you prefer a direct serial connection, in "make menuconfig"
 # select "Enable extra low-level configuration options" and select the