document that pico uses different pins

[joshua-8]

• Update pins to match the design/instructions for the first car to use a pico
• update documentation for the pins the pico uses

[joshua-8]

here's what it's set to currently v1.2.0

#if defined(ARDUINO_ARCH_MBED_RP2040)|| defined(ARDUINO_ARCH_RP2040)
///// joystick reader pins /////
byte JOY_X_PIN = A2;  // Analog input pin that the left-right potentiometer is attached to
byte JOY_Y_PIN = A0;  // Analog input pin that the forwards-backwards potentiometer is attached to

///// drive controller pins /////
byte LEFT_MOTOR_CONTROLLER_PIN = 3;
byte RIGHT_MOTOR_CONTROLLER_PIN = 4;

byte SPEED_KNOB_PIN = A1;

byte BUTTON_MODE_PIN = 2; // can turn button control mode on and off