### 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
source = self._parse(line, raise_if_invalid_or_disabled=True)[2]
        
        self._add_valid_source(source, comment, file=file or self._suggest_filename(source))
    def _remove_valid_source(self, source):
        
        for filename, n, enabled, src, comment in self:
            if source == src and enabled:
                self.files[filename].pop(n)
    def remove_source(self, line):
        source = self._parse(line, raise_if_invalid_or_disabled=True)[2]
        self._remove_valid_source(source)
class UbuntuSourcesList(SourcesList):
    LP_API = 'https://launchpad.net/api/1.0/~%s/+archive/%s'
    def __init__(self, module):
        self.module = module
        self.codename = module.params['codename'] or distro.codename
        super(UbuntuSourcesList, self).__init__(module)
        self.apt_key_bin = self.module.get_bin_path('apt-key', required=False)
        self.gpg_bin = self.module.get_bin_path('gpg', required=False)
        if not self.apt_key_bin and not self.gpg_bin:
            self.module.fail_json(msg='Either apt-key or gpg binary is required, but neither could be found')
    def __deepcopy__(self, memo=None):