Add our own block category to blocks.php (all block.json files are already set up for it).

[tcmulder]

/**
 * Add our own block category
 */
add_filter( 'block_categories' , function( $categories ) {
    $categories[] = array(
        'slug'  => 'aquamin-blocks',
        'title' => __( 'Custom Blocks', 'aquamin' ),
    );
    return $categories;
} );