### 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
pass
class SourcesList(object):
    def __init__(self, module):
        self.module = module
        self.files = {}  
        
        self.new_repos = set()
        self.default_file = self._apt_cfg_file('Dir::Etc::sourcelist')
        
        if os.path.isfile(self.default_file):
            self.load(self.default_file)
        
        for file in glob.iglob('%s/*.list' % self._apt_cfg_dir('Dir::Etc::sourceparts')):
            self.load(file)
    def __iter__(self):