Update events.yml

Author: dawnaitken

_data/events.yml

@@ -65,6 +65,6 @@
   - name: NDC 2025 Oslo
     start-date: 2025-05-19
     dates: May 19-23, 2025
-    url: https://ndcoslo.com/
-    optional-text: for discount tickets use the following link: https://event.checkin.no/82562/ndc-oslo-2025?action=campaignInvite&campaignInviteHash=ZGF3bi5haXRrZW5Ab3dhc3AuY29t&campaignInviteId=4927
+    url: https://event.checkin.no/82562/ndc-oslo-2025?action=campaignInvite&campaignInviteHash=ZGF3bi5haXRrZW5Ab3dhc3AuY29t&campaignInviteId=4927
+    optional-text: Above link is for discounted tickets