docs: add giswqs as a contributor for code, design, and maintenance

[allcontributors]

Adds @giswqs as a contributor for code, design, maintenance.

This was requested by giswqs in this comment

[skip ci]

[CLAassistant]

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.}