### 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
description:
        - Use an exponential backoff delay for each retry (see I(update_cache_retries)) up to this max delay in seconds.
        type: int
        default: 12
        version_added: '2.10'
    validate_certs:
        description:
            - If C(false), SSL certificates for the target repo will not be validated. This should only be used
              on personally controlled sites using self-signed certificates.
        type: bool
        default: 'yes'
        version_added: '1.8'
    filename:
        description:
            - Sets the name of the source list file in sources.list.d.
              Defaults to a file name based on the repository source url.
              The .list extension will be automatically added.
        type: str
        version_added: '2.1'
    codename:
        description:
            - Override the distribution codename to use for PPA repositories.
              Should usually only be set when working with a PPA on
              a non-Ubuntu target (for example, Debian or Mint).
        type: str
        version_added: '2.3'
    install_python_apt:
        description:
            - Whether to automatically try to install the Python apt library or not, if it is not already installed.
              Without this library, the module does not work.