Update `zh` translations for HOWTO and CODE_OF_CONDUCT

[DerenC]

What does this PR do?

Improve repo by translations zh for HOWTO and CODE_OF_CONDUCT. Refer to issue #6782.

Follow-up

• [x] Check the status of GitHub Actions and resolve any reported warnings!
• [x] I have checked, there is no ongoing PR that involves zh translations

Notes

• This is my first open source contribution. Please give me feedback on how can I improve or do better :)

[eshellman]

Needs review by a Chinese language reviewer.