Add slide deck for VDAms

Author: hannotify

.gitmodules

@@ -79,3 +79,6 @@
 [submodule "_slides/from-zero-to-secured/javaland-2025"]
 	path = _slides/from-zero-to-secured/javaland-2025
 	url = https://github.com/hannotify/from-zero-to-secured
+[submodule "_slides/javas-concurrency-journey-continues/voxxed-days-amsterdam-2025"]
+	path = _slides/javas-concurrency-journey-continues/voxxed-days-amsterdam-2025
+	url = https://github.com/hannotify/javas-concurrency-journey-continues