feat: custom content types backend

README.md

@@ -51,6 +51,7 @@ task dev                # API with hot reload + Vite HMR → http://localhost:51
 | [docs/performance.md](docs/performance.md) | Measured costs, such as the `?seo=` article filter |
 | [docs/api.md](docs/api.md) | API reference: authentication, API keys, routes and the activity log |
 | [docs/api/articles.md](docs/api/articles.md) | Reading articles: pagination, search, `format` and body schemas |
+| [docs/custom-content-types.md](docs/custom-content-types.md) | Custom content types: layering, phase 1 limitations and their fix path |
 | [docs/image-variants.md](docs/image-variants.md) | Image variants and their cache |
 | [docs/release-notes.md](docs/release-notes.md) | Release notes format, the published releases and how to publish one |