CLI default values

Would be nice to see the defaults of the command line arguments. Currently --help shows:

Usage: saqc [OPTIONS]

Options:
  -c, --config PATH               path to the configuration file  [required]
  -d, --data PATH                 path to the data file  [required]
  -o, --outfile PATH              path to the output file
  --scheme [float|simple|dmp|positional]
                                  the flagging scheme to use
  --nodata FLOAT                  nodata value
  --log-level [DEBUG|INFO|WARNING]
                                  set output verbosity
  --help                          Show this message and exit.