update README.md with instructions on item collection and hash generation

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

### Item collection

- For P.800 tests, these outputs need to be collected according to the test plan to assemble the final outputs required for P.800 test software.

  - This can be done using the scripts in [collection-scripts](collection-scripts/characterization/README.md) (click for README) by running:

  ```batch

  python collection-scripts\characterization\p800_categorized_samples.py

  python collection-scripts\characterization\p800_preliminaries.py

  ```

- For MUSHRA tests, the outputs may be used directly, or in case of multi-input format experiments again need to be manually assembled.

At this point of time there is no script to automatically perform this.

### Hash generation

The hashes for the `proc_final` (or `proc_output` for BS.1534 experiments) can be generated using the [get_md5.py](other/get_md5.py) script:

```shell

> python other/get_md5.py --help

usage: get_md5.py [-h] output_dir out_file

Cross-platform script for generating MD5 hashes of output files for the characterization testing experiments.

positional arguments:

  output_dir  Path to the output directory of the respective experiment that you want to generate Hashes for. Can be proc_output or proc_final.

  out_file    Output text file with filenames and Hashes

options:

  -h, --help  show this help message and exit

```

For example:

```shell

python other/get_md5.py experiments/characterization/P800-1/proc_final p800-1_hashes.txt

```

## Directory structure

    │   │   └── <item_name.wav.met> for MASA metadata

    │   ├── cat2...

    │   └── ...cat6

    ├── proc_final

    │   ├── c01

    │   │    └── [l]p[ee]a[y]s[zz].c[nn].wav

    │   ├── c02...

    │   ├── ...c36

    │   └── preliminaries

    │       └── [l]p[ee]a[y]s[zz].c[nn].wav

    └── proc_output

        ├── cat1

        │   ├── out_-16LKFS