Update! To get your wiki to show the domain name rather than the IP, once it resolves properly, please do the following:
Log in to your shell with ssh or kitty, then:
cd /var/www/html
vi LocalSettings.php
This will open up an editor called vi. The commands are a little different to use, so you can use whatever editor you might be familiar with. Or follow this directly:
Hit i to enter insert text mode.
Go down to the following line (where you will see your own IP):
$wgServer = "http://104.236.219.143";
And replace it with your domain name:
$wgServer = "http://atfmux.com";
Once you've done so, hit: :wq! (that's colon, then "wq!")
Your wiki should now be all set! I'll updated the tutorial, but I just wanted to make sure this step was known as I had accidentally left it out.