docs: document navbar dropdown link type

Co-Authored-By: Catherine Deskur <[email protected]>

Author: devin-ai-integration[bot]

fern/products/docs/pages/customization/what-is-docs-yml.mdx

@@ -242,10 +242,23 @@ navbar-links:
     rounded: false
   - type: github
     value: https://github.com/example-company/fern
+  - type: dropdown
+    text: Resources
+    icon: fa-solid fa-book
+    links:
+      - text: Documentation
+        href: https://example.com/docs
+        icon: fa-regular fa-file-lines
+      - text: API Reference
+        href: https://example.com/api
+        icon: fa-regular fa-code
+      - text: Tutorials
+        href: https://example.com/tutorials
+        icon: fa-regular fa-graduation-cap
 ```
 
 <ParamField path="type" type="enum" required={false} toc={true}>
-  One of `outlined`, `minimal`, `filled`, or `github`. This value controls the styling of the button. 
+  One of `outlined`, `minimal`, `filled`, `github`, or `dropdown`. This value controls the styling of the button. 
 </ParamField>
 
 <ParamField path="href" type="string" required={false} toc={true}>
@@ -274,6 +287,15 @@ navbar-links:
   By default, the `rightIcon` for a `filled` button is set to `arrow-right`.
 </ParamField>
 
+<ParamField path="links" type="list of objects" required={false} toc={true}>
+  Array of link objects to display in the dropdown menu. This field is used when `type` is set to `dropdown`. Each link object can have the following properties:
+  - `text` (string): The text to display for the link
+  - `href` (string): The URL the link points to
+  - `icon` (string): Optional [Font Awesome icon](https://fontawesome.com/icons) to display to the left of the text
+  - `rightIcon` (string): Optional [Font Awesome icon](https://fontawesome.com/icons) to display to the right of the text
+  - `rounded` (boolean): When `true`, the link will have fully rounded borders
+</ParamField>
+
 ## Footer links configuration
 
 Add clickable social media and community links to your documentation site footer to improve discoverability and engagement.