### Summary

Based on feedback from a mastodon ansible user:

The first example of https://docs.ansible.com/ansible/latest/collections/ansible/builtin/apt_key_module.html#examples (the apt_key replacement) shows how a pgp key is downloaded and declared as trusted for a repository, but there is no validation of the key going on. Maybe the get_url task could include the checksum argument, to show that (and how) the key should be validated against a known good. Further down there is also an example of apt_key downloading a key without the id argument specified.

### Issue Type

Documentation Report

### Component Name

apt_key

### Ansible Version

```console
$ ansible --version
2.15
```


### Configuration

```console
# if using a version older than ansible-core 2.12 you should omit the '-t all'
$ ansible-config dump --only-changed -t all
none
```


### OS / Environment

none

### Additional Information

The examples all use https URLs, so they do not expose you to just arbitrary MITM; but many projects use untrusted public mirrors to distribute packages and public keys, and instead post the fingerprint of the public key on the non-mirrored first-party website. You are then supposed to verify the downloaded key against that fingerprint (unfortunately a manual action since they post a PGP fingerprint and not a checksum), in order to protect against rogue mirror operators (AFAIK).

### Code of Conduct

- [X] I agree to follow the Ansible Code of Conduct
data = download_key(module, url)
        if filename:
            key_id = get_key_id_from_file(module, filename)
        elif data:
            key_id = get_key_id_from_data(module, data)
    r['id'] = key_id
    try:
        short_key_id, fingerprint, key_id = parse_key_id(key_id)
        r['short_id'] = short_key_id
        r['fp'] = fingerprint
        r['key_id'] = key_id
    except ValueError:
        module.fail_json(msg='Invalid key_id', **r)
    if not fingerprint:
        
        module.fail_json(msg="Unable to continue as we could not extract a valid fingerprint to compare against existing keys.", **r)
    if len(key_id) == 8:
        short_format = True
    
    r['before'] = keys = all_keys(module, keyring, short_format)
    keys2 = []
    if state == 'present':
        if (short_format and short_key_id not in keys) or (not short_format and fingerprint not in keys):
            r['changed'] = True
            if not module.check_mode:
                if filename:
                    add_key(module, filename, keyring)
                elif keyserver:
                    import_key(module, keyring, keyserver, key_id)
                elif data: