docs: add section about site-level landing page to products documentation (#2909)

Co-authored-by: fern-support <support@buildwithfern.com>
Co-authored-by: Fern Support <info@buildwithfern.com>

Author: devin-ai-integration[bot]

fern/products/docs/pages/navigation/products.mdx

@@ -143,6 +143,33 @@ If your `docs.yml` file includes a `navigation` field or a `tabs` field, be sure
 </Step>
 </Steps>
 
+### Add a site-level landing page
+
+You can add a landing page that appears at the root of your documentation site, independent of any product. This is useful when you want users to see an introductory page before selecting a product.
+
+Configure the `landing-page` property in your `docs.yml`:
+
+<CodeBlock title="docs.yml">
+```yaml
+landing-page:
+  page: Welcome
+  path: ./pages/welcome.mdx
+  slug: /welcome # optional
+
+products:
+  - display-name: Product A
+    path: ./products/product-a.yml
+  - display-name: Product B
+    path: ./products/product-b.yml
+```
+</CodeBlock>
+
+The landing page is not linked to any product and will be accessible at the root URL (or the specified slug) of your documentation site.
+
+<Note>
+For detailed configuration options, see the [landing page configuration reference](/learn/docs/configuration/site-level-settings#landing-page-configuration).
+</Note>
+
 ### Add versioning to your products
 
 You can optionally add versions to your internal products. Versioned and unversioned products can live next to each other in your site. Versions are not supported for external products.
@@ -350,4 +377,4 @@ The dropdown menus for product and version selectors can be customized using the
       <img src="webflow-version-selector.avif" alt="Example of a styled version selector" />
     </Frame>
   </Tab>
-</Tabs>                
+</Tabs>