A project I'm part of is forking the documentation of the original project which is licenced under CC BY-SA 3.0 (Creative Commons Attribution-ShareAlike 3.0 Unported License).
We obviously want to pay full attribution, I just don't want to be on the wrong side of anything here and want to make sure it is done properly, the last thing we want is to have a licencing mess later on when the project is more mature.
Essentially we are taking the original documentation and listing it in an archive section on the new website and modifying the original content fairly extensively to serve as the "new" documentation. Therefore both the original and new docs come from the original project.
Is it just as simple as creating a new licence in the root repo LICENCE.md file with attribution i.e.:
This work, "New Website", is a derivative of
[Old Website](https://LinkToOldRepo.com)by Old Team, used under CC BY-SA 3.0. "New Website" is licensed under CC BY-SA 3.0 by New Team.
I assume we are stuck with 3.0 as from what I understand it can't be upgraded to 4.0 easily.