Docs: Consolidate “How it works” guide and flesh out adapter docs

[alltheseas]

Warning

Docs have not been reviewed by a professional dev. Proceed at your own risk.

Summary

• add docs/how-it-works.md as the canonical architecture + quick-start doc,
  referenced from README.md
• refresh README.md with clearer doc links and an OS compatibility matrix
• expand each platform adapter README (Windows, macOS, Unix/AT-SPI, Android)
  with installation instructions, threading/runtime requirements, step-by-step
  initialization, and testing notes so integrators can follow consistent guidance

Testing

• not run (documentation-only changes)

[alltheseas]

e8c3d81

Updates Made - expands Winit, C, python bindings docs

• README.md:11-17 now links directly to the new C and Python binding guides so
  non-Rust consumers discover them from the main landing page.
• platforms/winit/README.md:1-60 was rewritten with dependency snippets,
  constructor guidance, an event-loop checklist, Unix feature notes, and testing
  instructions, making winit integrations self-serve.
• Added docs/c-bindings.md:1-49 detailing how to consume AccessKit via
• Added docs/python-bindings.md:1-55 covering pip installation, a minimal adapter
  example, maturin builds, and support links for the PyPI package.