[docs] Synology package install steps: install nodejs
### Analysis

Hello,

Thank you for making homebridge installable via synology package center.
This is just a small request to update the docs on how to install it since it took me a while to figure out.
After installing the package it was marked as running in package center, but opening the Web UI would result in a connection error (the server wasn't actually running).

I tried looking at the contents of the `/homebridge` folder and saw just the `package.json` file which led me to believe the install did not go through properly. After a while I figured out I need to manually install nodejs from the package center. After I did that and restarted homebridge it worked like a charm.

Please add this very important step to the docs to make sure other people don't struggle with it like I did.

All the best,
Dragos

### Expected Behavior

Should be able to install and get it working on first try.

### Steps To Reproduce

Install homebridge package on DSM7 without nodejs installed

### Logs

```markdown
none
```


### Configuration

```json
none
```


### Environment

- OS: DSM7
- Software: 
- Node: 18
- npm:


### Process Supervisor

hb-service

### Additional Context

_No response_