chore(debugging): add extra bullet point on top card group

Author: goosewin

fern/debugging.mdx

@@ -14,6 +14,7 @@ Voice agents involve multiple AI systems working together—speech recognition,
   <Card title="Speech & Understanding" icon="microphone">
     * Agent doesn't understand user input correctly
     * Responses are inappropriate or inconsistent
+    * Agent sounds robotic or unnatural
   </Card>
   <Card title="Technical & Integration" icon="gear">
     * Call quality issues or audio problems