### 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
valid = False
        enabled = True
        source = ''
        comment = ''
        line = line.strip()
        if line.startswith('#'):
            enabled = False
            line = line[1:]
        
        i = line.find('#')
        if i > 0:
            comment = line[i + 1:].strip()
            line = line[:i]
        
        
        source = line.strip()
        if source:
            chunks = source.split()
            if chunks[0] in VALID_SOURCE_TYPES:
                valid = True
                source = ' '.join(chunks)
        if raise_if_invalid_or_disabled and (not valid or not enabled):
            raise InvalidSource(line)
        return valid, enabled, source, comment
    @staticmethod
    def _apt_cfg_file(filespec):