add another document example

Author: devalog

fern/products/ask-fern/pages/features/documents.mdx

@@ -5,7 +5,7 @@ subtitle: Add custom data sources to Ask Fern.
 
 ## Overview
 
-You can extend Ask Fern's knowledge beyond your core documentation by indexing additional custom content. Adding materials such as internal FAQs, help desk tickets, knowledge base articles, marketing sites, and other resources helps Ask Fern provide more complete answers to developers.
+You can extend Ask Fern's knowledge beyond your core documentation by indexing additional custom content. Adding materials such as internal FAQs, help desk tickets, knowledge base articles, marketing sites, research papers, and other resources helps Ask Fern provide more complete answers to developers.
 
 The Documents API lets you upload, update, and delete custom documents that Ask Fern can reference when responding to user questions.