configureManifestPlugin(manifestPluginOptionsCallback = () => {}) {
        webpackConfig.configureManifestPlugin(manifestPluginOptionsCallback);

        return this;
    }
Allows you to configure the options passed to webpack-manifest-plugin.
A list of available options can be found at https://github.com/danethurber/webpack-manifest-plugin

For example:

```
Encore.configureManifestPlugin((options) => {
    options.fileName = '../../var/assets/manifest.json';
})
```

@param {OptionsCallback<object>} manifestPluginOptionsCallback
@returns {Encore}