Add Fern and Mintlify links to docs-agent.mdx

Author: dannysheridan

fern/examples/docs-agent.mdx

@@ -9,7 +9,7 @@ Try our live implementation using the voice widget in the bottom-right corner of
 ## Prerequisites
 
 - [Vapi account](https://dashboard.vapi.ai/) with API access
-- Documentation content - use your `llms-full.txt` file ([example](https://docs.vapi.ai/llms-full.txt)), available out-of-box on Fern/Mintlify
+- Documentation content - use your `llms-full.txt` file ([example](https://docs.vapi.ai/llms-full.txt)), available out-of-box on [Fern](https://buildwithfern.com/learn/docs/developer-tools/llms-txt) or [Mintlify](https://mintlify.com/docs/ai-ingestion#%2Fllms-full-txt)
 - [LlamaCloud account](https://cloud.llamaindex.ai/) for indexing
 
 ## Overview
@@ -251,4 +251,4 @@ You'll learn to:
   href='/prompting-guide'
 >
 Learn advanced prompting techniques to optimize your documentation agent's responses and behavior.
-</Card> 
+</Card>