add change to release-notes 5.12.0-M1

release-notes-5.12.0-M1-junit-jupiter-new-features-and-improvements
to be exact

Issue #3708

Author: JonasJebing

documentation/src/docs/asciidoc/release-notes/release-notes-5.12.0-M1.adoc

@@ -86,6 +86,11 @@ JUnit repository on GitHub.
   a test-scoped `ExtensionContext` in `Extension` methods called during test class
   instantiation. This behavior will become the default in future versions of JUnit.
 * `@TempDir` is now supported on test class constructors.
+* `@ParameterizedTest`s now support argument count validation as an experimental feature.
+  With the `junit.jupiter.params.argumentCountValidation=strict` configuration
+  or the `@ParameterizedTest(argumentCountValidation = ArgumentCountValidationMode.STRICT)` attribute,
+  any mismatch between the declared number of arguments and the number of arguments provided by the arguments source
+  will result in an error. By default there is only an error if there are less arguments provided than declared.
 
 
 [[release-notes-5.12.0-M1-junit-vintage]]