Update app.py

Author: CoderCpy

streamlit/flight_routes/app.py

@@ -10,7 +10,7 @@
 st.title('Flight Route Finder')
 
 st.markdown('This app uses historical flight data to visualize Non-Stop Flight Routes from '
-            'any Country and Airport in the database.')
+            'any Country and Airport in the database. Choose Country first, then Airport.')
 
 data_url = 'https://raw.githubusercontent.com/CoderCpy/Python_projects/refs/heads/main/data/flightroute/'
 csv_file = 'flight_routes.csv'