Add paragraph about problems on OS X in release

docs/announce/2014.11.md

@@ -29,6 +29,14 @@ Some of the changes in this release are outlined below:
 These are only some of the changes in this release. For a more
 detailed list, see "docs/ChangeLog".
 
+A note for OS X users: when running a spectest with a high number of parallel
+tests (e.g. with TEST_JOBS=8), it is likely you will see any number between
+0 and 10 test-files with failures, usually because they abort midway through
+testing.  Running these test-files then by themselves, shows no errors
+whatsoever.  Current theory is that something in the MoarVM build on OS X is
+introducing random memory corruption.  Any thoughts / suggestions / fixes will
+be deeply appreciated.
+
 The development team thanks all of our contributors and sponsors for
 making Rakudo Perl possible, as well as those people who worked on
 Parrot, the Perl 6 test suite, MoarVM and the specification.