Update README with multiple UARTs support

Signed-off-by: Álvaro Fernández Rojas <[email protected]>

README.md

@@ -1,9 +1,19 @@
 Raspberry Pi Pico USB-UART Bridge
 =================================
 
-This program bridges the Raspberry Pi Pico HW UART0 to USB CDC serial device in order to behave like any other USB-to-UART Bridge controller.
+This program bridges the Raspberry Pi Pico HW UARTs to two independent USB CDC serial devices in order to behave like any other USB-to-UART Bridge controllers.
 
 Disclaimer
 ----------
 
 This software is provided without warranty, according to the MIT License, and should therefore not be used where it may endanger life, financial stakes, or cause discomfort and inconvenience to others.
+
+Raspberry Pi Pico Pinout
+------------------------
+
+| Raspberry Pi Pico GPIO | Function |
+|:----------------------:|:--------:|
+| GPIO0 (Pin 1)          | UART0 TX |
+| GPIO1 (Pin 2)          | UART0 RX |
+| GPIO4 (Pin 6)          | UART1 TX |
+| GPIO5 (Pin 7)          | UART1 RX |