When I was in Azure last year we used an internal Git repo named, I think it was named 'onebranch'. There are only two things we posted to a private github.

First was our description of our JSON apis, which would eventually be sent to a public github.

The second was some internal documentation we had for our internal clients. I don't think there were any 'secrets' in there, but it would be documentation for the internal side for internal clients that no outsider could ever use.