Java: Add change note.

Author: aschackmull

java/ql/lib/change-notes/2024-06-17-ffbl-implicit-this.md

@@ -0,0 +1,7 @@
+---
+category: minorAnalysis
+---
+* A bug has been fixed in the heuristic identification of uncertain control
+  flow, which is used to filter data flow in order to improve performance and
+  reduce false positives. This fix means that slightly more code is identified
+  and hence pruned from data flow.