I asked about this a bit over a year ago – all the keyboard shortcuts are for Macs only. Most people don’t use Macs, especially outside of the US.
There was also this thread on the Mac-only keyboard shortcuts, opened almost two years ago: Dumb Question: Why is "Control" denoted "Cmd" in the docs?
I submitted some trivial edits last year to help fix the shortcuts in the manual. Not sure what happened to them – it’s still Mac only (I didn’t really know how to use Github then, so I might have missed a follow-up, but I thought that the Atom team was going to fix the docs the rest of the way.)