update README.md

- This can be somewhat worked around with a shell loop, but please note this can make finding an error more difficult:

```sh

# for POSIX shells

for config in $(ls experiments/characterization/P800-1/config/*.yml); do python3 -m ivas_processing_scripts $config; done

```

```batch

:: for cmd

for %f in (experiments\characterization\P800-1\config\*.yml) do python -m ivas_processing_scripts "%f"

```

## Follow up tasks

After the processing is finished, the outputs will be present in the respective `proc_output` directories.