ext_tables.php

<?php
defined('TYPO3_MODE') || die('Access denied.');

call_user_func(
    function ($extKey) {
        $dokType = \FBIT\PageReferences\Domain\Model\ReferencePage::DOKTYPE;

        // Add new page type:
        $GLOBALS['PAGES_TYPES'][$dokType] = [
            'type' => 'web',
            'allowedTables' => '*',
        ];

        // Add the new doktype to the list of types available from the new page menu at the top of the page tree
        \TYPO3\CMS\Core\Utility\ExtensionManagementUtility::addUserTSConfig(
            'options.pageTree.doktypesToShowInNewPageDragArea := addToList(' . $dokType . ')'
        );

        // Provide icon for page tree, list view, ... :
        \TYPO3\CMS\Core\Utility\GeneralUtility::makeInstance(\TYPO3\CMS\Core\Imaging\IconRegistry::class)
            ->registerIcon(
                'apps-pagetree-page-reference',
                TYPO3\CMS\Core\Imaging\IconProvider\SvgIconProvider::class,
                [
                    'source' => 'EXT:' . $extKey . '/Resources/Public/Icons/apps-pagetree-page-reference.svg',
                ]
            );

        \TYPO3\CMS\Core\Utility\ExtensionManagementUtility::addStaticFile('FBIT.' . $extKey, 'Configuration/TypoScript', 'Page References Management');
    },
    'fbit_pagereferences'
);