Fix label of required flags

Signed-off-by: Luca Clementi <luca.clementi@gmail.com>
minor touch to output of -q -S

Signed-off-by: Luca Clementi <luca.clementi@gmail.com>
more fixes to the documetation in README.md

Signed-off-by: Luca Clementi <luca.clementi@gmail.com>