feat: docs scaffolding using mkdocs.yml

[HackStrix]

This pull request introduces a comprehensive documentation site for the project using MkDocs with the Material theme. It adds a new documentation structure covering architecture, deployment, SDKs, and installation guides, and configures the site navigation, theme, and build requirements.

Documentation content:

• Added new documentation markdown files for architecture (dual-mode.md, singleflight.md, tracking.md), Go library (install.md, pool.md, workers.md), daemon usage (install.md, cli.md, uds.md), SDKs (python.md, elixir.md), deployment (kubernetes.md, bare-metal.md), and introductory materials (index.md, quickstart.md). [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15]

Documentation site configuration:

• Added mkdocs.yml to define site metadata, navigation, theme options, markdown extensions, and structure for the new documentation site.
• Added requirements-docs.txt specifying MkDocs and MkDocs Material as dependencies for building the documentation site.