docs: Document directory based archetypes

See #4535

docs/content/en/content-management/archetypes.md

@@ -70,6 +70,28 @@ It will create a new newsletter type of content file based on the archetype temp
 The above _newsletter type archetype_ illustrates the possibilities: The full Hugo `.Site` and all of Hugo's template funcs can be used in the archetype file.
 
 
+## Directory based archetypes
+
+Since Hugo `0.49` you can use complete directories as archetype templates. Given this archetype directory:
+
+```bash
+archetypes
+├── default.md
+└── post-bundle
+    ├── bio.md
+    ├── images
+    │   └── featured.jpg
+    └── index.md
+```
+
+```bash
+hugo new --kind post-bundle post/my-post
+```
+
+Will create a new folder in `/content/post/my-post` with the same set of files as in the `post-bundle` archetypes folder. All content files (`index.md` etc.) can contain template logic, and will receive the correct `.Site` for the content's language.
+
+
+
 [archetypes directory]: /getting-started/directory-structure/
 [content types]: /content-management/types/
 [front matter]: /content-management/front-matter/