Add comprehensive README documentation for OpenTrace docs site

[Umaaz]

Summary

This PR adds a comprehensive README file to document the OpenTrace documentation repository, providing developers with setup instructions, project structure overview, and deployment information.

Key Changes

• Development Setup: Added prerequisites and local development instructions for running the documentation site locally using MkDocs
• Project Structure: Documented the complete directory layout including docs organization, configuration files, and dependencies
• Deployment Documentation: Clarified the automated GitHub Actions deployment process for both production and preview environments
• Workflow Reference: Added a table documenting the CI/CD workflows (deploy.yml and cleanup-preview.yml) and their triggers

Notable Details

• Local dev server runs on http://127.0.0.1:3009
• Production deployments are triggered by pushes to the main branch
• Preview deployments are automatically created for all other branches and cleaned up when branches are deleted
• The documentation covers all major sections including integrations, capabilities, workflows, and legal documents

https://claude.ai/code/session_016wHZkMFCL6SDDKJx8EBWCT

[github-actions]

📚 Documentation Preview

Preview deployed to: https://opentrace.github.io/docs/preview/19-merge/