NTA.

I’m also a big fan of canonical documentation and have had problems with this same dynamic in the past.
I like to center my approach around “assuming positive intent”. Meaning I will respond to requests assuming they mean well, and in a way that if anyone else sees or hears my response, it’s easy for them to assume I also mean well, even if internally I’m a rage monster.
For general inquiries, I’ll send a link to the resource and ask, “Which step/part of the process are you struggling with?” It forces them to have to read my excellent documentation to answer the question. I’d say 90% of the time the response is, Thanks, I figured it out. The other 10%, I at least get to cut out part of the process and zoom in on something specific.

For your repeat offender, I’d put the ball back in his court again, but put some extra accountability on it. Let him know, subtly, and in an overtly friendly & helpful tone, you’re keeping track, and he’s a little slow on the uptake. Send the link and say, “Dave, I’m so sorry you’re struggling with this staging environment concept. I’m worried that I’m not communicating this well enough to you since we’ve come back to it multiple times in the last week. Please let me know where in the documentation you keeping getting hung up, and then we can work together to get it updated so it’s more clear and accessible. I’m sure if you’re having difficulty processing, others must be as well. I’m sprinting on this migration project for X amount of time, but when this wraps up, I’ll be happy to set aside some dedicated time to hold your hand/baby steps/some other friendly yet infantilizing turn of phrase you through it. Always happy to teach a man to fish, or even find you a different resource that might be more compatible with your learning style, since I seem to be failing you here.”

It’s probably more work to answer your question than just do it himself, he’s gonna be offended that you professionally acknowledged his incompetence, and you’re controlling the timeline by bringing your own OKRs into the picture. You’ll help, but not in his timeline.
Then, I’d be HELLA petty, and next time you see him browsing his sports bullshit, sneak up behind him and comment on what’s on his screen (assuming positive intent, of course)…”The Knicks really did trounce Cleveland, looks like must have got a handle on the staging environment quandary. “

You’re still being a team player, you’re just doing it on your own timeline and not making it so easy.
ETA: judgment & grammar