Correct IGN layer link in map page

IGN layer does not work anymore.

This seems to be the new link

added Frontend Priority: high labels

assigned to @remi.bisson

created branch 89-correct-ign-layer-link-in-map-page to address this issue

mentioned in merge request !42 (merged)

mentioned in merge request !41 (merged)

closed with merge request !41 (merged)

mentioned in commit 230d294e