[Starlingx-discuss] [docs] Update developer wiki for adding new repo

Hello Kristal, As part of effort to apply for CNCF Certified Kubernetes logo, we need to mirror our repositories to GitHub. I've completed adding zuul job to sync all existing repos that are required to upload to GitHub. For future development, I'd like to add some notes to the StarlingX development wiki for how to create a zuul job to sync repo from opendev to GitHub. Can you provide guidance on how to make the doc changes? Thanks, Bin