### 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
"MemoryAccounting": "no",
            "MemoryLimit": "18446744073709551615",
            "MountFlags": "0",
            "Names": "crond.service",
            "NeedDaemonReload": "no",
            "Nice": "0",
            "NoNewPrivileges": "no",
            "NonBlocking": "no",
            "NotifyAccess": "none",
            "OOMScoreAdjust": "0",
            "OnFailureIsolate": "no",
            "PermissionsStartOnly": "no",
            "PrivateNetwork": "no",
            "PrivateTmp": "no",
            "RefuseManualStart": "no",
            "RefuseManualStop": "no",
            "RemainAfterExit": "no",
            "Requires": "basic.target",
            "Restart": "no",
            "RestartUSec": "100ms",
            "Result": "success",
            "RootDirectoryStartOnly": "no",
            "SameProcessGroup": "no",
            "SecureBits": "0",
            "SendSIGHUP": "no",
            "SendSIGKILL": "yes",
            "Slice": "system.slice",
            "StandardError": "inherit",
            "StandardInput": "null",
            "StandardOutput": "journal",