### 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
repo:
        description:
            - A source string for the repository.
        type: str
        required: true
    state:
        description:
            - A source string state.
        type: str
        choices: [ absent, present ]
        default: "present"
    mode:
        description:
            - The octal mode for newly created files in sources.list.d.
            - Default is what system uses (probably 0644).
        type: raw
        version_added: "1.6"
    update_cache:
        description:
            - Run the equivalent of C(apt-get update) when a change occurs.  Cache updates are run after making changes.
        type: bool
        default: "yes"
        aliases: [ update-cache ]
    update_cache_retries:
        description:
        - Amount of retries if the cache update fails. Also see I(update_cache_retry_max_delay).
        type: int
        default: 5
        version_added: '2.10'
    update_cache_retry_max_delay: