Additional Documentation

Firstly, thank you for the plugin. I’ve managed to index CPTs for now using the available documentation and I have a few questions to ask

1.) How to add additional attributes that don’t belong to a Custom Post type. I’ll add the code of how I used to get it done using “WP search with Algolia” plugin.

/* Algolia customisations */
/* Indexing Grade */
add_filter( 'algolia_post_shared_attributes', 'grade_post_attributes', 10, 2 );
add_filter( 'algolia_searchable_post_shared_attributes', 'grade_post_attributes', 10, 2 );

/**
 * @param array   $shared_attributes
 * @param WP_Post $post
 *
 * @return array
 */
function grade_post_attributes( array $shared_attributes, WP_Post $post ) {	
	if ( 'book-review' !== $post->post_type ) {
		// We only want to add an attribute for the 'resource' post type.
		// Here the post isn't a 'resource', so we return the attributes unaltered.
		return $shared_attributes;
	}
	$shared_attributes['grade'] = get_post_meta( $post->ID, 'wpcf-book-grade', true );
	// Always return the value we are filtering.
	return $shared_attributes;
}

I want to know how to do it with this plugin.

2. How do I add InstantSearch Widgets or use their API to add searchable filters etc to the widgets using additional parameters ?

thanks