Extended board support package (XBSP) for the Raspberry Pi Pico.

This crate extends the official pico_bsp from Jeremy Grosser with additional, reusable components. It is designed for general use in any Ada project targeting the RP2040-based Raspberry Pi Pico and is not limited to the Pi Ada Tutorial.

It is developed in parallel with the Pi Ada Tutorial and therefore also supplies the exact support packages used in the tutorial chapters. This dual role makes pico_xbsp equally suitable for:

• Standalone embedded Ada projects that only need the extra functionality, and
• Readers following the tutorial who want ready-made, well-documented building blocks.

Current content:

1. Pico.Analog - Simplified analogue GPIO using Pulse Width Modulation (PWM).
2. Pico.UART_IO - Simplified UART Text Output (Input comes later).

All packages are supplied with complete GNATDOC annotations.

GNATdoc documentation: https://pi-ada-tutorial.sourceforge.io/gnatdoc/

SourceForge repository: https://sourceforge.net/projects/pi-ada-tutorial/

The crate will grow with each new tutorial chapter while remaining a clean, independent library.