### Summary

The `apt_repository` will fail with a somewhat confusing error if gnugp, and dirmngr manager are not installed.  Neither of these packages are Required/Essential/Important, and may not be already installed in minimal systems that you might want to run `apt_repository` on.

The fix might be to just include `gnupg` in the requirements section of the docs.

### Issue Type

Documentation Report

### Component Name

apt_repository

### Ansible Version

```console
$  ansible --version
ansible [core 2.11.4]
  config file = ...
  configured module search path = ...
  ansible python module location = ...
  ansible collection location = ...
  executable location = /usr/local/bin/ansible
  python version = 3.9.2 (default, Feb 28 2021, 17:03:44) [GCC 10.2.1 20210110]
  jinja version = 3.0.1
  libyaml = True
```


### Configuration

```console
$ ansible-config dump --only-changed
```


### OS / Environment

Mostly a docs issue so this is N/A. But apt_repository applies to Debian, Ubuntu, and forks.

### Additional Information

Tells people that need gnupg when using apt_repository.

### Code of Conduct

- [X] I agree to follow the Ansible Code of Conduct
version_added: '2.10'
    update_cache_retry_max_delay:
        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(no), 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: