[TASK] [DOCS] Improve documentation structure with HLD in doc folder

[LGSI-KarumuriHari]

📝 Task Description

Reorganize and improve the documentation structure in the /doc folder to enhance clarity, maintainability, and ease of navigation. This includes:

• Standardizing folder hierarchy and file naming conventions
• Ensuring consistency between /doc/architecture, /doc/contribution, and /doc/docs
• Updating internal cross-references and links
• Aligning documentation structure with the gRPC architecture migration
• Creating clear separation between HLD (High-Level Design) and API documentation

📋 Checklist

• Audit current documentation structure in /doc folder
• Standardize folder naming (e.g., /doc/docs → /doc/user-guide or similar)
• Update all internal cross-references between documentation files
• Ensure architecture documentation references are consistent
• Verify all links in documentation files are valid
• Add/update navigation index or table of contents

🔗 Related Requirement

Relates to #28

📐 Implementation Guidelines

Reference files:

• Current structure: /doc/architecture/, /doc/contribution/, /doc/docs/
• Architecture docs: timpani_architecture.md, grpc_architecture.md
• User-facing docs: api.md, developments.md, getting-started.md
• Follow existing SPDX license headers in all documentation files
• Maintain consistency with Rust migration documentation (gRPC/Protobuf references)

🧪 Testing Method

• Verify all internal links work correctly
• Check that documentation structure is intuitive for new contributors
• Validate cross-references between HLD and API documentation
• Ensure README.md files point to correct documentation paths

[LGSI-KarumuriHari]

@basheerFZ Please assign this task to me ,
and the parent for this issue would be #28 ..