Update IGN API key

Fixes #8509

examples/wmts-ign.js

@@ -37,12 +37,11 @@ const tileGrid = new WMTSTileGrid({
   matrixIds: matrixIds
 });
 
-// API key valid for 'openlayers.org' and 'localhost'.
-// Expiration date is 06/29/2018.
-const key = '2mqbg0z6cx7ube8gsou10nrt';
+// For more information about the IGN API key see
+// https://geoservices.ign.fr/blog/2017/06/28/geoportail_sans_compte.html
 
 const ign_source = new WMTS({
-  url: 'https://wxs.ign.fr/' + key + '/wmts',
+  url: 'https://wxs.ign.fr/pratique/geoportail/wmts',
   layer: 'GEOGRAPHICALGRIDSYSTEMS.MAPS',
   matrixSet: 'PM',
   format: 'image/jpeg',