docs: adds change note for linq where fixes

Author: baywet

csharp/ql/src/change-notes/2026-09-03-missed-where-terminal-branches.md

@@ -0,0 +1,4 @@
+---
+category: minorAnalysis
+---
+* The `cs/linq/missed-where` query no longer flags `foreach` loops where the matching branch terminates the method, iterator, or loop instead of continuing with filtered loop work.