Update Gradio interface description to clarify that all results are returned

ui/gradio_interface.py

@@ -165,6 +165,10 @@ class GradioInterface:
                 """
                 This system helps you research topics by searching across multiple sources
                 including Google (via Serper), Google Scholar, and arXiv.
+                
+                The system will return ALL results from each search engine, up to the maximum
+                number specified by the "Results Per Engine" slider. Results are ranked by
+                relevance across all sources.
                 """
             )