update licence

LICENSE

@@ -2,15 +2,15 @@
 
 | Folder          | Source                     | License                                   |
 |-----------------|----------------------------|-------------------------------------------|
-| `trajectories/` | OpenSky Network (Trino)    | OpenSky Network Data License Agreement — non-profit research/education only. Redistributed with written permission of the OpenSky Network. |
+| `trajectories/` | OpenSky Network (Trino)    | OpenSky Network Data License Agreement — non-profit research/education only. Redistributed with written permission of the OpenSky Network. (https://opensky-network.org/about/terms-of-use) |
 | `splits/`       | Own work                   | CC BY 4.0                                 |
-| `terrain/`      | Copernicus DEM GLO-90, retrieved via the Copernicus Data Space Ecosystem Sentinel Hub Process API (`demInstance: COPERNICUS_90`) | Licence for the use of the Copernicus WorldDEM-90 |
-| `runways/`      | X-Plane Scenery Gateway    | GNU GPL v2                                |
-| `osm/`          | OpenStreetMap contributors | ODbL 1.0                                  |
+| `terrain/`      | Copernicus DEM GLO-90, retrieved via the Copernicus Data Space Ecosystem Sentinel Hub Process API (`demInstance: COPERNICUS_90`) | Full, Free & Open licence for the Copernicus WorldDEM-90 (https://opencamphq.com/attribution) |
+| `runways/`      | X-Plane Scenery Gateway    | GNU GPL v2 (https://xpguard.net/licenses)                              |
+| `osm/`          | OpenStreetMap contributors | ODbL 1.0 (https://www.openstreetmap.org/copyright/)                    |
 | `procedures/`   | AIRAC API (airac.net)      | no license listed. |
 
 ## Required notices
 - Cite: Schäfer et al., "Bringing up OpenSky: A large-scale ADS-B sensor network for research", IPSN 2014.
 - Produced using Copernicus WorldDEM-90 © DLR e.V. 2010-2014 and © Airbus Defence and Space GmbH 2014-2018 provided under COPERNICUS by the European Union and ESA; all rights reserved.
-- The organisations in charge of the Copernicus programme by law or by delegation do not incur any liability for any use of the Copernicus WorldDEM-30.
+- The organisations in charge of the Copernicus programme by law or by delegation do not incur any liability for any use of the Copernicus WorldDEM-90.
 - © OpenStreetMap contributors, available under the Open Database License (ODbL).