more informative warning

app.py

@@ -77,7 +77,7 @@ def show_credits():
     
 if file_url is None:
     st.warning(
-    "Please provide a KML or GeoJSON URL as a query parameter, e.g., `?file_url=<your_file_url>` or upload a file."
+    "Please provide a KML or GeoJSON URL as a query parameter, e.g., `https://sustainabilitylabiitgn-ndvi-perg.hf.space?file_url=<your_file_url>` or upload a file."
     )
     show_credits()
     st.stop()