Magento2: Custom attribute of category. Add default value in all existing category once we InstallData script

Here I need to Add defaul value of my custom category attribute in all existing category while I install the script.

here is my code:

<?php

namespace CommercePundit\HtmlSitemap\Setup;

use Magento\Eav\Setup\EavSetupFactory;
use Magento\Framework\Setup\UpgradeDataInterface;
use Magento\Framework\Setup\ModuleDataSetupInterface;
use Magento\Framework\Setup\ModuleContextInterface;


class UpgradeData implements UpgradeDataInterface {

private $eavSetupFactory;

public function __construct(EavSetupFactory $eavSetupFactory) {
    $this->eavSetupFactory = $eavSetupFactory;
}

public function upgrade( ModuleDataSetupInterface $setup, ModuleContextInterface $context)
{
    if ( version_compare( $context->getVersion(), '1.0.1', '<' ) ) {

        $eavSetup = $this->eavSetupFactory->create(['setup' => $setup]);

        $eavSetup->addAttribute(\Magento\Catalog\Model\Category::ENTITY, 'category_sitemap' , [
            'type' => 'int',
            'label' => 'Include in HTML Sitemap',
            'input' => 'select',
            'source' => \Magento\Eav\Model\Entity\Attribute\Source\Boolean::class,
            'default' => '1',
            'sort_order' => 11,
            'global' => \Magento\Eav\Model\Entity\Attribute\ScopedAttributeInterface::SCOPE_STORE,
            'used_in_product_listing' => true, 
            'visible_on_front' => true, 
            'is_used_in_grid' => true, 
            'is_visible_in_grid' => true,
        ]);
    }
}
}

And if it is wrong way that what I am doing then please suggest me the way of achieving this.