update release notes
diff --git a/WHATSNEW b/WHATSNEW
index 2358d92..55817aa 100644
--- a/WHATSNEW
+++ b/WHATSNEW
@@ -88,7 +88,8 @@
optimized and simplified many thread-related functions.
-eliminated resource leak races in thread cancellation.
+eliminated resource leak races in thread cancellation. (almost all
+existing implementations, including glibc, have these leaks.)
overhauled stdio implementation to take advantage of readv/writev for
reduced syscall load, and improved stdio's handling of error status.