If your next question is about shaping the site, open the configuration guide. If the question is about what the authoring surface can do, go to Markdown writing features. Diagram-specific behavior lives in the Mermaid guide and the D2 guide, while shell styling and theme presets are covered in theming.
Use security when the site needs login or path rules, architecture demo when you want the request and rendering model in graph form, and advanced behavior when you are past the happy path and want the edges. The items/tasks graph surface now supports markdown links inside attr values like spec: [API](guide#api), plus group color inheritance where child nodes use the nearest colored parent group unless they set their own color. Shared palettes can live in one JSON file via color_palette_source: shared-palettes.json with node_color_palettes and edge_color_palettes inside it.
The manual itself starts at vyasa manual/README.md, but you should not need it before the quick start above works.