### Summary

The [list of builtin modules](https://docs.ansible.com/ansible/latest/collections/ansible/builtin/index.html) shows two modules with similar names and identical descriptions:

> [systemd module](https://docs.ansible.com/ansible/latest/collections/ansible/builtin/systemd_module.html#ansible-collections-ansible-builtin-systemd-module) – Manage systemd units
> [systemd_service module](https://docs.ansible.com/ansible/latest/collections/ansible/builtin/systemd_service_module.html#ansible-collections-ansible-builtin-systemd-service-module) – Manage systemd units

My guess was that `systemd_service` would manage services running with systemd, and `systemd` would manage `systemd` itself. But the description is identical. The synopsis is identical. The arguments and examples appear identical.

As a user, I expect that if one module has two names, the documentation would state that one is an alias.

Looking at [the code](https://github.com/ansible/ansible/blob/devel/lib/ansible/modules/systemd.py) I see that `systemd` is symlinked to `systemd_service.py`.

Please modify the documentation to state that one is an alias of the other, and they are identical.


### Issue Type

Documentation Report

### Component Name

systemd_service

### Ansible Version

```console
N/A
```


### Configuration

```console
N/A
```


### OS / Environment

N/A

### Additional Information

For context, my objective is to create a service file, and then enable+start it. I was hoping that there would be one module to do that. But then I saw there are two similar ones, and I thought one would create the .service file, and the other would load+run it. But that doesn't appear to be the case either.

### Code of Conduct

- [X] I agree to follow the Ansible Code of Conduct
parsed[k] = v.strip()
                k = None
        else:
            multival.append(line)
            if line.rstrip().endswith('}'):
                parsed[k] = '\n'.join(multival).strip()
                multival = []
                k = None
    return parsed
def main():
    
    module = AnsibleModule(
        argument_spec=dict(
            name=dict(type='str', aliases=['service', 'unit']),
            state=dict(type='str', choices=['reloaded', 'restarted', 'started', 'stopped']),
            enabled=dict(type='bool'),
            force=dict(type='bool'),
            masked=dict(type='bool'),
            daemon_reload=dict(type='bool', default=False, aliases=['daemon-reload']),
            daemon_reexec=dict(type='bool', default=False, aliases=['daemon-reexec']),
            scope=dict(type='str', default='system', choices=['system', 'user', 'global']),
            no_block=dict(type='bool', default=False),
        ),
        supports_check_mode=True,
        required_one_of=[['state', 'enabled', 'masked', 'daemon_reload', 'daemon_reexec']],
        required_by=dict(
            state=('name', ),
            enabled=('name', ),
            masked=('name', ),
        ),