02 Hello World GPU: update rank number

There is a small typo: rank 0 is sending and rank 1 is receiving.

02-MSA-hello-world-gpu/solutions/hello-world.cu

@@ -51,7 +51,7 @@ int main(int argc, char** argv){
     CUDA_RT_CALL( cudaPeekAtLastError() );
     CUDA_RT_CALL( cudaDeviceSynchronize() );
     
-    // TODO: Implement the MPI_Recv() call to receive the "payload" from rank 1 using directly "d_payload" as the target buffer on the GPU
+    // TODO: Implement the MPI_Recv() call to receive the "payload" from rank 0 using directly "d_payload" as the target buffer on the GPU
     if (rank == 1) {
         MPI_Recv(d_payload, 6, MPI_CHAR, 0, tag, MPI_COMM_WORLD, &stat);
     }