Add render reference asset manifest contract

docs/examples-index.md

@@ -42,6 +42,7 @@ This index maps example files to practical usecases and useful commands.
 | Files | Usecase | Try |
 | --- | --- | --- |
 | `examples/render/fake-render-request.yaml` | Deterministic render/export contract fixture | Use with the `render.fake` API adapter; no external renderer required |
+| `examples/render/render-reference-manifest.yaml` | Render unit, cross-reference, TOC, asset, and source-map manifest fixture | Load with `RenderReferenceManifest.from_dict`; no renderer or asset copying required |
 
 ## Cache, Backend, Policy, And Context