Improve README dependency graph visualization example

[lukasniessen-bain]

Context

ArchUnitTS already supports dependency graph reporting through projectGraph() / dependencyGraph(), including DOT, Mermaid, D2, CSV, JSON, and HTML exports plus focus/reachability/collapse/external/self-dependency options.

The README has a concise Dependency Graph Reports section, but it currently does not show a rendered example image and the example is generic. Also, includeSelfDependencies() exists in the graph API but is not listed in the README graph exploration options.

Task

Update the README graph reporting section so it stays brief and matches the existing README style, while adding a clear visual example.

Suggested direction:

• Generate a readable dependency graph from a known TypeScript/JavaScript repository, preferably a compact/familiar one such as zod or another project that stays legible when focused or collapsed.
• Add the generated image to the repo assets and embed it in the README with useful alt text.
• Keep the section concise: explain the gist, show how to export a report, and mention the available formats/options without turning it into a long tutorial.
• Add any missing public graph options to the README, including includeSelfDependencies().

Acceptance Criteria

• README includes an embedded dependency graph example image.
• The example is based on a recognizable TypeScript/JavaScript repository and remains readable in the README.
• The section briefly explains how to use graph reports and lists the supported formats/options, including includeSelfDependencies().
• The wording and length fit the style of the surrounding README feature sections.