Hi,
We have an issue for this kind of functionality https://github.com/GetPublii/Publii/issues/274
Do you think that adding options where user can specify a CDN domain/path for specific types of files will be enough?
Regarding documentation – we are working on an internal solution which will allow us to store Publii posts and some config/assets on the Github repository and then sync them in the site in Publii so I do hope that at the beginning of the next year, Publii docs will be fully available and editable for the community 🙂