Updating release notes

doc/ReleaseNotes4.9.txt

@@ -40,6 +40,10 @@ should be transparent to most users.  `TestWatchman` has been deprecated,
 and replaced by `TestWatcher`, which has the same functionality, but implements
 the new type.
 
+`TestRule` is an abstract base class, and its abstract `apply` method is 
+protected.  In order to apply `TestRule`s to a `Statement`, use the `RunRules`
+class in `org.junit.rules`.
+
 ### LICENSE checked in ###
 
 The Common Public License that JUnit is released under is now included
@@ -61,3 +65,5 @@ in the source repository.
 
 - Backed out unused folder "experimental-use-of-antunit", replaced by 
   bash-based script at build_tests.sh
+
+- Made MultipleFailureException public, to assist extension writers.