Update README.md

Author: ye-luo

README.md

@@ -1,12 +1,15 @@
-# A collection of OpenMP tests
+A collection of OpenMP tests for C++ and Fortran compilers
 
+Recipe example
+```
 mkdir build_gcc_omp
 cd build_gcc_omp
 cmake -DCMAKE_CXX_COMPILER=g++ -DCMAKE_Fortran_COMPILER=gfortran \
       -DCMAKE_CXX_FLAGS=-fopenmp -DCMAKE_Fortran_FLAGS=-fopenmp \
       ..
 make -k -j 16
 ctest
+```
 
 ###
 OpenMP offload compiler options