Add data source licenses

Author: culka

src/main/resources/templates/index.html

@@ -83,8 +83,11 @@
                             'https://cdn.digitransit.fi/map/v3/hsl-map/{z}/{x}/{y}.png?digitransit-subscription-key=' + digitransitKey
                         ],
                         tileSize: 512,
-                        attribution:
-                            'Map tiles &copy; by <a target="_top" rel="noopener" href="https://digitransit.fi/">Helsinki Region Transport 2021</a>, under <a target="_top" rel="noopener" href="http://creativecommons.org/licenses/by/4.0">CC BY 4.0</a>.'
+                        attribution: [
+                            'Map tiles &copy; by <a target="_top" rel="noopener" href="https://digitransit.fi/">Helsinki Region Transport 2021</a>, under <a target="_top" rel="noopener" href="http://creativecommons.org/licenses/by/4.0">CC BY 4.0</a>.',
+                            'Road data &copy; by <a href="https://vayla.fi/en/transport-network/data/digiroad/data" target="_blank" rel="noopener noreferrer">Digiroad, Finnish Transport Agency CC BY 4.0.</a>',
+                            'Tram rail data &copy; by <a href="https://www.maanmittauslaitos.fi/en/opendata-licence-cc40" target="_blank" rel="noopener noreferrer">National Land Survey of Finland Topographic Database 01/2026 CC BY 4.0.</a>'
+                        ].join(' | ')
                     }
                 },
                 layers: [