feat(docs-nested-collections): add expected structure (#4969)

website/content/docs/beta-features.md

@@ -22,13 +22,13 @@ backend:
 
 # when using the default proxy server port
 local_backend: true
-
 ```
 
 3. Run `npx netlify-cms-proxy-server` from the root directory of the above repository.
-    - If the default port (8081) is in use, the proxy server won't start and you will see an error message. In this case, follow [these steps](#configure-the-netlify-cms-proxy-server-port-number) before proceeding.
+
+   * If the default port (8081) is in use, the proxy server won't start and you will see an error message. In this case, follow [these steps](#configure-the-netlify-cms-proxy-server-port-number) before proceeding.
 4. Start your local development server (e.g. run `gatsby develop`).
-5. Open [http://localhost:8000/admin](http://localhost:8000/admin) to verify that your can administer your content locally.
+5. Open <http://localhost:8000/admin> to verify that your can administer your content locally.
 
 **Note:** `netlify-cms-proxy-server` runs an unauthenticated express server. As any client can send requests to the server, it should only be used for local development.
 
@@ -51,10 +51,8 @@ local_backend:
   url: http://localhost:8082/api/v1
   # when accessing the local site from a host other than 'localhost' or '127.0.0.1'
   allowed_hosts: ['192.168.0.1']
-
 ```
 
-
 ## GitLab and BitBucket Editorial Workflow Support
 
 ***added in netlify-cms@2.10.6 / netlify-cms-app@2.11.3***
@@ -614,3 +612,18 @@ collections:
     # moving an existing entry will move the entire sub tree of the entry to the new location
     meta: { path: { widget: string, label: 'Path', index_file: 'index' } }
 ```
+
+Nested collections expect the following directory structure:
+```
+content
+└── pages
+    ├── authors
+    │   ├── author-1
+    │   │   └── index.md
+    │   └── index.md
+    ├── index.md
+    └── posts
+        ├── hello-world
+        │   └── index.md
+        └── index.md
+```