docs: add cainiao1992 as a contributor for doc

[allcontributors]

Adds @cainiao1992 as a contributor for doc.

This was requested by rayrayraykk in this comment

[cla-assistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}