www: clarify what MadMPI benchmark is

public/mpibenchmark/index.html.in

@@ -41,6 +41,11 @@
       <h1>
 	MadMPI benchmark
       </h1>
+
+      <p>
+	<i>MadMPI benchmark</i> is benchmark designed to assess the performance of MPI libraries using various metrics.
+	It may be used to benchmark any MPI library and is not tied to <a href="../newmadeleine/#madmpi">MadMPI</a>.
+      </p>
       <p>
 	MadMPI benchmark contains the following benchmark series:
       </p>