Getting started guide: wrong flag given

https://hedgerules.micahrl.com/docs/guides/getting-started/#5-deploy-edge-rules

### 5. Deploy edge rules

```
hedgerules deploy --site public/
```

When issueing this command, an error occurs:

```
$ hedgerules deploy
error: output-dir is required (set in config file or via --output-dir)
```

Therefore, the correct command is:

```
hedgerules deploy -output-dir public/
```


