Add documentation on repository management point of view (e.g. setup, update of CI)

[himorin]

From recent activities (like #151 ), I suppose there could be rapid changes on tools which we are using for automatic processing and we need to perform bulk update by external reasons. So, I would propose to have a document for describing what we prepare for IWWG/IWCG, listing items considered/enabled for customization per repository, and listing FAQs and limitations for organizers of repositories.
@Yonet @AdaRoseCannon @cwilso is this ok?

For now, I've noticed on customization:

• list based push to gh-pages at depth-sensing repository Update GHActions/JamesIves/github-pages-deploy-action to 4.0.0 for all repos #151 (comment)
• additional rule for kicking actions Add a rule to enable manually dispatching the workflow depth-sensing#17 (comment)