Update changelog to mention new member conflict rules.

Closes https://github.com/dart-lang/sdk/issues/33237

Change-Id: Ic2b477013534190ccf725b119b85f167c5cd2727
Reviewed-on: https://dart-review.googlesource.com/62802
Commit-Queue: Aske Simon Christensen <askesc@google.com>
Reviewed-by: Erik Ernst <eernst@google.com>
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 66137b6..b944e07 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,11 @@
 
 ### Language
 
+* New member conflict rules have been implemented. Most cases of conflicting
+  members with the same name are now static errors. Issue [33235][issue 33235].
+
+[issue 33235]: https://github.com/dart-lang/sdk/issues/33235
+
 #### Strong Mode
 
 ### Dart VM