### 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
"StartLimitAction": "none",
            "StartLimitBurst": "5",
            "StartLimitInterval": "10000000",
            "StatusErrno": "0",
            "StopWhenUnneeded": "no",
            "SubState": "running",
            "SyslogLevelPrefix": "yes",
            "SyslogPriority": "30",
            "TTYReset": "no",
            "TTYVHangup": "no",
            "TTYVTDisallocate": "no",
            "TimeoutStartUSec": "1min 30s",
            "TimeoutStopUSec": "1min 30s",
            "TimerSlackNSec": "50000",
            "Transient": "no",
            "Type": "simple",
            "UMask": "0022",
            "UnitFileState": "enabled",
            "WantedBy": "multi-user.target",
            "Wants": "system.slice",
            "WatchdogTimestampMonotonic": "0",
            "WatchdogUSec": "0",
        }
'''  
import os
from ansible.module_utils.basic import AnsibleModule
from ansible.module_utils.facts.system.chroot import is_chroot
from ansible.module_utils.service import sysv_exists, sysv_is_enabled, fail_if_missing
from ansible.module_utils.common.text.converters import to_native
def is_running_service(service_status):