Clarify pythonLocation behavior for PyPy and GraalPy in environment variables

[aparnajyothi-y]

Description:
This PR enhances the documentation for the pythonLocation environment variable in advanced-usage.md by clarifying how the path to the python executable differs across implementations (CPython, PyPy, GraalPy) and platforms (Linux/macOS, Windows).

Check list:

[ X] Mark if documentation changes are required.

[Copilot]

Pull Request Overview

This PR improves the documentation for the pythonLocation environment variable by adding detailed information about how different Python implementations (CPython, PyPy, GraalPy) organize their directory structures and where the Python executable is located within each implementation.

Key Changes:

• Enhanced the pythonLocation environment variable description with implementation-specific executable paths
• Added platform-specific path examples for Linux/macOS and Windows
• Clarified directory structure differences between Python implementations

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}