Add metadata for various 2026 events

Author: hannotify

_data/events.yml

@@ -15,6 +15,11 @@
   logo: voxxed-days-amsterdam.png
   appearances:
     - id: when-music-and-software-come-together
+      sessionPageUrl: https://m.devoxx.com/events/vdams26/talks/1772/when-music-and-software-come-together
+      slides:
+        source: google-drive
+        url: https://docs.google.com/presentation/d/e/2PACX-1vRNHtmP0c9GygUW6_bB01_1G8RwVGFdU6y00--Uk9qFXVZnw0BAZyBjQffHLyEAnu340vly6X-Heycz/pub
+
 
 - id: exec-ut-2026
   name: exec(ut)
@@ -31,8 +36,11 @@
   dateStart: 2026-03-26
   logo: execut.png
   appearances: 
-    - id: todo
+    - id: what-stairway-to-heaven-can-teach-us-about-software-development
       sessionPageUrl: https://execut.nl/programme
+      slides:
+        source: google-drive
+        url: https://docs.google.com/presentation/d/e/2PACX-1vS5fObb9KViyrayfKk7Pw8hwxoToSjxkjrHEFjpVTogF3mLH4Vj6eAH_9meMcprLmITqNCihrl3zMN4/pub
 
 - id: brabantjug-2026
   name: BrabantJUG
@@ -46,7 +54,8 @@
   dateStart: 2026-03-18
   logo: brabantjug.avif
   appearances:
-    - id: todo
+    - id: will-git-be-around-forever
+      sessionPageUrl: https://www.meetup.com/brabant-jug/events/313380952/
 
 - id: javaland-2026
   name: JavaLand
@@ -66,6 +75,7 @@
   appearances:
     - id: javas-concurrency-journey-continues
       sessionPageUrl: https://meine.doag.org/events/javaland/2026/agenda/#eventDay.1773183600
+      githubUrl: https://github.com/hannotify/structured-concurrency-bar
       slides:
         source: local