Fixed badge URL.
Fixed badge URL.

HTTPS sits complain about an unsafe image, because the license badge was loaded
non-HTTPS.

RWTH-HPC/PnMPI,RWTH-HPC/PnMPI,RWTH-ELP/PnMPI,RWTH-HPC/PnMPI,RWTH-ELP/PnMPI,RWTH-ELP/PnMPI