FacetWP - stick custom data into FWP_JSON

functions.php

<?php

add_filter( 'facetwp_assets', function( $assets ) {

    // Populate "FWP_JSON.neighborhood_data"
    FWP()->display->json['neighborhood_data'] = array(
        'academy' => array(
            'title' => 'Academy',
            'description' => 'This is the description',
            'image' => 'http://image.url',
        ),
        'airport' => array(
            'title' => 'Airport',
            'description' => 'This is the description',
            'image' => 'http://image.url',
        )
    );

    // Return the same thing (since we're hijacking this hook)
    return $assets;
});