Please document the reversed headers for non-fysetc 12864 LCD connection

[yuriy-yarosh]

Example of connecting RepRapDiscount 128x64 with Klipper to Cheetah2

# v0_display.cfg

######################################################################
# "RepRapDiscount 128x64 Full Graphic Smart Controller" type displays
######################################################################

[display]
lcd_type: st7920
cs_pin: EXP2_4
sclk_pin: EXP2_5
sid_pin: EXP2_3
click_pin: ^!EXP2_2
encoder_pins: ^EXP1_3, ^EXP1_5
#kill_pin: ^!EXP1_8

spi_bus: spi
spi_software_miso_pin: EXP1_1
spi_software_mosi_pin: EXP1_6
spi_software_sclk_pin: EXP1_2

[output_pin beeper]
pin: EXP2_1

# Cheetah pinout

# EXP1	  
# SD-MISO	PA6   22 EXP1_1
# SD-SCK	PA5   21 EXP1_2
# BTN_EN1	PC10  51 EXP1_3
# SD-SS         PA4   20 EXP1_4
# BTN_EN2	PC11  52 EXP1_5
# SD-MOSI	PA7   23 EXP1_6
# SD-DET	PC3   11 EXP1_7
# RESET	        NRST  7	 EXP1_8     
# GND	GND	      NA EXP1_9
# 5V	5V	      NA EXP1_10

# EXP2
# BEEP     	PC9 	40	EXP2_1
# BTN_ENC	PC12	53	EXP2_2
# LCD_EN	PB15	36	EXP2_3
# LCD_RS	PB12	33	EXP2_4
# LCD_D4	PB13	34	EXP2_5
# LCD_D5	PB14	35	EXP2_6
# LCD_D6	PB6     58	EXP2_7
# LCD_D7	PB7     59	EXP2_8
# GND	GND	NA	        EXP2_9
# 5V	5V	NA	        EXP2_10

#
# Modified reversed pinout
#
[board_pins]
aliases:
  EXP1_10=<5V>, EXP1_8=<RST>, EXP1_6=PA7,  EXP1_4=PA4,  EXP1_2=PA5,
  EXP1_9=<GND>, EXP1_7=PC3,   EXP1_5=PC11, EXP1_3=PC10, EXP1_1=PA6,

  EXP2_10=<5V>, EXP2_8=PB7, EXP2_6=PB14, EXP2_4=PB12, EXP2_2=PC12,
  EXP2_9=<GND>, EXP2_7=PB6, EXP2_5=PB13, EXP2_3=PB15, EXP2_1=PC9,

# https://github.com/Klipper3d/klipper/blob/master/config/sample-lcd.cfg#L129
# Reversed Plug pin locations

# The following diagram shows the correct location of pin 1 
# along with ground and power pins on the EXP1 and EXP2 plugs:
#
#          EXP1:                        EXP2:
#   +-----------------+          +-----------------+
#   |  o  o  o  o  5V |          |  o  o  o  o  o  | -->> EXP1 on Cheetah
#   |  1  o  o  o GND |          |  1  o  o  o GND |
#   +------     ------+          +------     ------+
#
# Reversing the headers is important because STM32 NRST is on EXP1 Cheetah.
#
# Cheetah board has the cutout in the wrong location.
# Make a cutout either on the Cheetah board or on the LCD board directly and reverse the headers.
#
#          EXP1:                        EXP2:
#   +-----|     |-----+          +-----|     |-----+
#   |  o  o  o  o  5V |          |  o  o  o  o  o  | -->> EXP1 on Cheetah
#   |  1  o  o  o GND |          |  1  o  o  o GND |
#   +------     ------+          +------     ------+
#