### 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
if changed and not module.check_mode:
        try:
            sourceslist.save()
            if update_cache:
                err = ''
                update_cache_retries = module.params.get('update_cache_retries')
                update_cache_retry_max_delay = module.params.get('update_cache_retry_max_delay')
                randomize = random.randint(0, 1000) / 1000.0
                for retry in range(update_cache_retries):
                    try:
                        cache = apt.Cache()
                        cache.update()
                        break
                    except apt.cache.FetchFailedException as e:
                        err = to_native(e)
                    
                    delay = 2 ** retry + randomize
                    if delay > update_cache_retry_max_delay:
                        delay = update_cache_retry_max_delay + randomize
                    time.sleep(delay)
                else:
                    revert_sources_list(sources_before, sources_after, sourceslist_before)
                    module.fail_json(msg='Failed to update apt cache: %s' % (err if err else 'unknown reason'))
        except (OSError, IOError) as ex:
            revert_sources_list(sources_before, sources_after, sourceslist_before)
            module.fail_json(msg=to_native(ex))
    module.exit_json(changed=changed, repo=repo, state=state, diff=diff)
if __name__ == '__main__':
    main()