Document that the mutex module is now gone.
diff --git a/Misc/NEWS b/Misc/NEWS
index 4cf9353..24a63ec 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -20,6 +20,8 @@
 
 - The user module has been removed.
 
+- The mutex module has been removed.
+
 - The imputil module has been removed.
 
 Build