[tldoc] Update Request for texlive-zh-cn Document on TUG Website

[Karl Berry]

    Subject: [tldoc] Update Request for texlive-zh-cn Document on TUG Website

Hi again Ran - it's intentional that the links on
https://tug.org/texlive/doc.html go to the last released version, rather
than what's currently in the repo, since there are often doc updates
during the year which apply to the upcoming release.

However, in this case, it makes sense to use the development zh-cn
version that you just provided, so I repointed the link. (And made a
note to switch it back after the 2025 release.)

Thanks,
Karl