Update README.md

GYSELAX/testcase_gpu/README.md

@@ -17,7 +17,7 @@ Case\_MPI64 on 8 nodes:
  - Total time:  325.34 s
  - Total time (without init & diag): 230.47 s
 
-The total time and the compute time (total time without initialization and diagnostics) are the two key indicators for the porting on GPU.
+The compute time (total time without initialization and diagnostics) is the time indicator for the part of the application targeted to be ported on GPU.
   
 The number of OpenMP threads can be set depending on your machine. 
 Please, read the section **Add a new machine** in the application [README](../README.md).