Update README.md

Author: DongweiYe

README.md

@@ -18,7 +18,8 @@ Each example consists of three main procedures: preprocessing, finite element si
   - Parametrize the geometry and compute reduced parameters of geometry
 
 * We provide three .edp here:
-  - `ReferNS_transient_parallel.edp` is designed for performing finite-element simulations (transient) with various shapes of domains on a reference domain (paralleled with PETSc). This step generates the geometry-informed snapshots for ROM. Implement with `ff-mpi -np 16 ReferNS_transient_parallel.edp -v 0`
+  - `ReferNS_transient_parallel.edp` is designed for performing finite-element simulations (transient) with various shapes of domains on a reference domain (paralleled with PETSc). This step generates the geometry-informed snapshots for ROM.
+    Implement with `ff-mpirun -np 16 ReferNS_transient_parallel.edp -v 0` where 16 stands for the number of cores for mpi.
   - `StandardNS.edp` is the standard finite-element simulation for the flow on its original domain. It is used for validation of the solution achieved on the reference domain
   - `ReferNS.edp` is designed for performing finite-element simulations (steady-state) with various shapes of domains on a reference domain. This step generates the geometry-informed snapshots for ROM (currently out-of-date, not using).