Add localization for `thousand` in zh_CN

[dofine]

I forked the repo and edited localization for thousand in zh_CN (while wondering why it was not localized before), see dofine@c6eaf06 .
But as a newbie, I don't know how to test it and get merged. :( Maybe someone could give some help.

[hugovk]

Hello!

Here's instructions from GitHub on how to create what's called a "pull request", or PR, which is how to propose changes to the project:

https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/proposing-changes-to-your-work-with-pull-requests/creating-a-pull-request

For example, you can go to:

main...dofine:humanize:main

And then fill out the template with your changes.

If you include the magic phrase "Fixes #126" then when the PR is merged, it will automatically close this issue.

Then click "Create pull request", and it will then start some automated testing.

Let me know if you need any more help.

Thanks!