docs: fix rclone plugin install flag in volumes guide (#26459)

## Description

The rclone example in the volumes guide installs the plugin with
`--aliases rclone`. `docker plugin install` has no `--aliases` flag, so
the command fails before it reaches the daemon:

```console
$ docker plugin install --grant-all-permissions rclone/docker-volume-rclone --aliases rclone
unknown flag: --aliases
```

The flag is `--alias` ("Local name for plugin"), as listed in the
[`docker plugin install`
reference](https://docs.docker.com/reference/cli/docker/plugin/install/)
and used in the [rclone Docker plugin docs](https://rclone.org/docker/).
The later steps in the guide use `-d rclone` and `volume-driver=rclone`,
so they need the plugin to be installed under that alias.

I checked the flag parsing with Docker CLI 29.1.3 against a non-existent
daemon socket: `--aliases` fails with `unknown flag`, while `--alias
rclone` parses and only fails to connect. `npx --no-install rumdl fmt`
and `scripts/lint.sh` (rumdl 0.2.49, Vale 3.17.0) report no issues on
the changed line.

## Related issues or tickets

None.

## Reviews

- [ ] Technical review
- [ ] Editorial review
- [ ] Product review

content/manuals/engine/storage/volumes.md

@@ -554,7 +554,7 @@ host and can connect to the second node using SSH.
 On the Docker host, install the `rclone/docker-volume-rclone` plugin:
 
 ```console
-$ docker plugin install --grant-all-permissions rclone/docker-volume-rclone --aliases rclone
+$ docker plugin install --grant-all-permissions rclone/docker-volume-rclone --alias rclone
 ```
 
 ### Create a volume using a volume driver