Refine NEWS entry for helgrind Ada tasks intercepts


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@14048 a5019735-40e9-0310-863c-91ae7b9d1cf9
diff --git a/NEWS b/NEWS
index 1c746fc..6c2cac1 100644
--- a/NEWS
+++ b/NEWS
@@ -19,7 +19,9 @@
     the list of locks, their location, and their status.
   - Helgrind now understands the Ada task termination rules
     and creates a 'H-B relationship' between a terminated task and
-    its master. This only works with gnatpro >= 7.3.0w-20140611
+    its master. This avoids some false positive and avoids big
+    memory usage when a lot of Ada tasks are created and terminated.
+    The interceptions are only activated with gnatpro >= 7.3.0w-20140611
     or gcc >= ????? (TBD: check when changes pushed to FSF gcc).
 
 * Callgrind: