Chapter 11, 'Promises, async/await', assumes knowledge of DOM manipulation not yet taught

DOM manipulation is not covered in this tutorial until four chapters later, in Part 2. From the comments, it looks like some are ready for it and some are not. I don't know if the async stuff could be explained well without using DOM examples, and I haven't looked at the DOM chapter much, so don't know if it requires stuff from Part 1 beyond Chapter 10, but maybe it could be moved up, or referenced, or some short primer or in-context explanations provided to get people unfamiliar with the subject through the async chapter.

第11章「Promises, async/await」を、Part 2のDOM章および既存のコメントと併せてレビューする。章を移動するべきか、後の教材を参照するべきか、入門解説を追加するべきかを判断し、そのうえで編集前に明確な指導方針と完了基準を定める。