Explain what `--move-path-to-operation` does

When I do help - `--move-path-to-operation` has no description.

```
./node_modules/.bin/oas-toolkit merge --help

oas-toolkit merge

merge the provided OpenAPI files

Opcje:
--help Pokaż pomoc [boolean]
--version Pokaż numer wersji [boolean]
--move-path-to-operation [boolean]
```

Start at the `merge --help` entry point and locate the definition of `--move-path-to-operation` in the CLI. Add a description so the option is explained in the generated help output, then run `oas-toolkit merge --help` and confirm the description appears.

Written by the indexing model from the issue text.