Direct Copying from GitHub?

I am editing an article which links directly to their GitHub Guidebook.

I understand following guidelines, but it seems as though he copied their entire guidebook from that link.

Is this proper?

Great question.

Yes, in some cases, contributors will submit articles based on articles from their blogs or from GitHub repos. This is totally fine if they originally authored the content (or if they’re part of a team that did so, and they’re clarifying that unambiguously).

Sometimes I will even approach people who’ve created great blog posts / GitHub repositories and ask them if they’d be interested in cross-posting.

Thank you.
That was helpful.
I’ll check for author-ship when I see it again.