Improve local development instructions in the tutorial

I'm trying to get started with the easiest example from the tutorial at https://reactjs.org/tutorial/tutorial.html#setup-for-the-tutorial for some hours now. I desperately looking for the location where to put the ShoppingList, Square`, etc. classes. I invested some time in understanding the terms, but it always falls back to the contradiction in the instructions

Delete all files in the src/ folder of the new project

and

Note:
Don’t delete the entire src folder, just the original source files inside it. We’ll replace the default source files with examples for this project in the next step.

This is the same as

Delete the original source files in src.

right (where the attribute original is still unclear because all files are original after creating the app with npx)? If not, I'm not getting it after reading it the fifth time.

Furthermore, I don't find any instructions where to put the code in the tutorial. My only guess is src/index.js, but that doesn't lead to the code being displayed after npm start.

I think that creating the app with content and then deleting it is a worse approach than build the application from scratch. Unfortunately, dependencies and tools like package managers seem to be already designed more as soon-to-be outdated rather than doing one good job for a long time in the "frontend world" - which is why most other tutorials on React going the way to build from scratch are outdated these days. The solution for this problem would be to simply put the tutorial commands in a CI script and test them periodically.

从链接 URL 中教程的“Setup for the Tutorial”部分开始，将有关删除 src 中文件的说明与后面的代码示例进行比较。验证文档中 ShoppingList 和 Square 的放置位置以及 npm start 流程；当一个新应用能够按照说明操作并在无需猜测的情况下显示教程代码时，这项工作就完成了。