updated Readme according to new benchmark

halo_exchange/README.md

@@ -163,7 +163,7 @@ Hardware: Supermuc Phase 1 Thin Nodes. Intel Sandy Bridge-EP Xeon E5-2680 8C @2.
 
 Commandline: 
 
-	mpiexec -n {ranks} ./8_unstructured_haloex {flags} -v1 -n 10M -i100
+	mpiexec -n {ranks} ./8_unstructured_haloex {flags} -v1 -n 1M -i1000
 	
 where `{ranks}` is the number of cores, `{flags}` is [`collective`, `p2p`, `p2p-sync`, `p2p-ready`].
 As Supermuc Phase 1 Thin nodes are 8 core dual socket systems, 16 tasks per node are used.