Documentation Cleanup and Rustdoc Deployment Improvements

[MozirDmitriy]

Description

This pull request addresses #2091 Documentation Cleanup by reorganizing and improving the project documentation, enhancing cross-references, and automating the deployment of Rust API documentation.
Key changes include:

• Reorganized and clarified the structure of the docs/ folder, adding cross-links between the main README and documentation index.
• Updated docs/README.md and docs/vm/README.md to improve navigation and reference benchmark results.
• Added links to benchmark results and extended documentation in the main README.md.
• Enhanced vm/src/lib.rs with module-level rustdoc, including links to the main README and documentation, and mentioning mermaid diagram support.
• Added the aquamarine dev-dependency to enable mermaid diagrams in rustdoc.
• Updated the GitHub Actions workflow (.github/workflows/bench.yml) to build and deploy Rust API documentation (cargo doc) to GitHub Pages alongside benchmark results.
  These changes make the documentation more discoverable, up-to-date, and easier to maintain, while also ensuring that both benchmarks and API docs are always available online.

Checklist

• Linked to Github Issue
• Unit tests added
• Integration tests added.
• This change requires new documentation.
  • Documentation has been added/updated.
  • CHANGELOG has been updated.