Add a link to 2019 Rust developer survey's Chinese translation

[juntao]

Hello,

Since Chinese is now the second most popular language among Rust developers, we translated the developer survey blog post into Chinese and inserted a link into the blog post.

If this is not the way to publicize translations, please let me know. I am just trying to help. :)

cheers
Michael Yuan

[rust-highfive]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @nikomatsakis (or someone else) soon.

If any changes to this PR are deemed necessary, please add them as extra commits. This ensures that the reviewer can see what has changed since they last reviewed the code. Due to the way GitHub handles out-of-date commits, this should also make it reasonably obvious what issues have or haven't been addressed. Large or tricky changes may require several passes of review and changes.

Please see the contribution instructions for more information.

[nikomatsakis]

Thanks!