### Summary

The [`filename` parameter docs](https://docs.ansible.com/ansible/latest/collections/ansible/builtin/apt_repository_module.html#parameter-filename) don't give enough info to tell how the file name is generated.

I believe my `repo: deb https://packagecloud.io/linz/prod/ubuntu/ {{ ansible_distribution_release }} main` is hanging indefinitely ~~, and I suspect this has something to do with the file name being a duplicate, resulting in a background prompt which is never printed or dismissed, but it's hard to tell based on the [code](https://github.com/ansible/ansible/blob/f3be331c9cb2f2c6edeb0bdf28a1e8a9681d727c/lib/ansible/modules/apt_repository.py#L235-L258)~~ (Based on copying the code into a Python interpreter it looks like the generated file name is `packagecloud_io_linz_prod_ubuntu.list`, which looks fine.).

### Issue Type

Documentation Report

### Component Name

lib/ansible/modules/apt_repository.py

### Ansible Version

```console
N/A
```


### Configuration

```console
N/A
```


### OS / Environment

N/A

### Additional Information

N/A

### Code of Conduct

- [X] I agree to follow the Ansible Code of Conduct
module = AnsibleModule(
        argument_spec=dict(
            repo=dict(type='str', required=True),
            state=dict(type='str', default='present', choices=['absent', 'present']),
            mode=dict(type='raw'),
            update_cache=dict(type='bool', default=True, aliases=['update-cache']),
            update_cache_retries=dict(type='int', default=5),
            update_cache_retry_max_delay=dict(type='int', default=12),
            filename=dict(type='str'),
            
            install_python_apt=dict(type='bool', default=True),
            validate_certs=dict(type='bool', default=True),
            codename=dict(type='str'),
        ),
        supports_check_mode=True,
    )
    params = module.params
    repo = module.params['repo']
    state = module.params['state']
    update_cache = module.params['update_cache']
    
    sourceslist = None
    if not HAVE_PYTHON_APT: