port r12811 from 1.1: Add changelog for the "scheduling" state in traces

ChangeLog

@@ -30,6 +30,8 @@ The scheduling context release
 New features:
   * The reduction init codelet is automatically used to initialize temporary
     buffers.
+  * Traces now include a "scheduling" state, to show the overhead of the
+    scheduler.
 
 StarPU 1.1.1 (svn revision 12638)
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