Add organization authentication settings

[asyd]

Add step to configuration google authentication in organization settings.

[dcramer]

I'm not sure this makes a lot of sense. We'd be duplicating information that we'd have to maintain between multiple repos of docs. We can say "Configuration happens within your organization's authentication settings in the UI" or similar. To some degree I would expect users to rely on user docs and not system docs (which is what the repo is - a system extension), but I understand that not everyone would end up down that same path of reading.