### 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
f.write(line)
                    except IOError as ex:
                        self.module.fail_json(msg="Failed to write to file %s: %s" % (tmp_path, to_native(ex)))
                self.module.atomic_move(tmp_path, filename)
                
                if filename in self.new_repos:
                    this_mode = self.module.params.get('mode', DEFAULT_SOURCES_PERM)
                    self.module.set_mode_if_different(filename, this_mode, False)
            else:
                del self.files[filename]
                if os.path.exists(filename):
                    os.remove(filename)
    def dump(self):
        dumpstruct = {}
        for filename, sources in self.files.items():
            if sources:
                lines = []
                for n, valid, enabled, source, comment in sources:
                    chunks = []
                    if not enabled:
                        chunks.append('# ')
                    chunks.append(source)
                    if comment:
                        chunks.append(' # ')
                        chunks.append(comment)
                    chunks.append('\n')
                    lines.append(''.join(chunks))
                dumpstruct[filename] = ''.join(lines)
        return dumpstruct
    def _choice(self, new, old):