gsoc26: Documentation cleanup and restructuring

[DhanashreePetare]

Description

Revise and organizing the project documentation.

Required changes

1. Keep the Quickstart section in the root README.md.
2. Keep the DBpedia section, but remove repeated Docker commands.
3. Mention Docker once in the documentation, then use Python-only commands throughout.
4. Add a GSOC 2026 section to the root README.md.
5. Move detailed CLI documentation to: /doc/cli-usage.md
6. Move module usage documentation to: /doc/module-usage.md
7. Move examples and related documentation to: /doc/examples/
8. Add /doc/README.md if needed to provide an overview and navigation for the documentation.
9. Keep the Development & Contribution section.