fix typo in doc
fix typo in doc

michkot/benchexec,martin-neuhaeusser/benchexec,cheshire/benchexec,sosy-lab/benchexec,dbeyer/benchexec,ultimate-pa/benchexec,IljaZakharov/benchexec,ultimate-pa/benchexec,sosy-lab/benchexec,martin-neuhaeusser/benchexec,IljaZakharov/benchexec,martin-neuhaeusser/benchexec,ultimate-pa/benchexec,sosy-lab/benchexec,dbeyer/benchexec,IljaZakharov/benchexec,bjowac/impara-benchexec,cheshire/benchexec,cheshire/benchexec,ultimate-pa/benchexec,bjowac/impara-benchexec,ultimate-pa/benchexec,ultimate-pa/benchexec,dbeyer/benchexec,sosy-lab/benchexec,martin-neuhaeusser/benchexec,dbeyer/benchexec,bjowac/impara-benchexec,sosy-lab/benchexec,michkot/benchexec,IljaZakharov/benchexec,michkot/benchexec,sosy-lab/benchexec