Add changelog for 3.3.1-RC4

Author: Kordyjan

changelogs/3.3.1-RC3.md

@@ -10,6 +10,6 @@ According to `git shortlog -sn --no-merges 3.3.1-RC2..3.3.1-RC3` these are:
 
 ```
      2 Paweł Marks
-     1 Martin Odersky
+     1 Nicolas Stucki
 
 ```

changelogs/3.3.1-RC4.md

@@ -0,0 +1,15 @@
+# Backported fixes
+
+- Revert "Include top-level symbols from same file in outer ambiguity error" [#17438](https://github.com/lampepfl/dotty/pull/17438)
+
+# Contributors
+
+Thank you to all the contributors who made this release possible 🎉
+
+According to `git shortlog -sn --no-merges 3.3.1-RC3..3.3.1-RC4` these are:
+
+```
+     2 Paweł Marks
+     1 Nicolas Stucki
+
+```