Can't make it work

I'm new to both this plugin and gitbook.

I've tried to install this plugin by editing my `book.json` like this:
```json
{
"root": "./docs/",
"plugins": ["prism", "-highlight"]
}
```

It doesn't work, the syntax highlighting is still the default one from Gitbook and the languages supported by prism and not the default Gitbook's highlight doesn't hightlight at all...

Is there anything else to do to install this plugin?

Start by reproducing the reported behavior with the supplied book.json configuration and inspect the plugin's GitBook installation entry points. Confirm whether Prism is loaded and whether its supported languages are highlighted; done means the documented configuration works and the reported languages no longer fall back to GitBook's default highlighting.

Written by the indexing model from the issue text.