That’s actually fine (for me). I reviewed the tomcat guide again and it still feels “jumpy”. Allow me to give only one exampe: The second bullet point is already a link again give enough memory to Java. I’d prefer to have reasonable default here and a “for more info see memory settings section” link. Which could then also be referenced to by the current OOM error debug section.
This may cause a little redundancy but should be better for most. And if one gets surprised be the very high popularity of your xwiki installation (which I wish for every xwiki installation 
) one may need to adjust. If you run a “special needs” installation, like high volume or high availibity demands, you know it normally and plan ahead accordingly.
This could be nice, actually I liked the wizard for remi’s php repository, which admittedly covers a way simpler topic. I don’t know if this is “worth” it, maybe it is the detail that signs the deal, maybe it’s just a little sugar on the top.
Maybe it could be used for some new cool dynamic page type in our wikis too, wouldn’t that be awesome?
A cheaper and faster option is to dedicate a special section for user contributed howtos, where you see very concrete descriptions of installations, like installing “xwiki 9.x on centos 7.x with tomcat 8.x and mysql 5.x”. I see a lot of benefits from this: First that would encourage users to edit documentation, second you as a user may find “your” required walkthrough already “readymade” and third there may be nice little tricks and hints to get “inspired” even for the official documentation.
That may be possible, but it may be also the case that it is some kind of “catch-all” configuration, when you you don’t have docker or debian available. So it is somewhat natural that you see quite a lot of installations for this configuration.
Getting more complex stuff out of sight is always a good idea. I’d also propose to move the docker method to the production ready methods yet maybe below the debs. I also like the docker-hub description a lot.
Writing good documentation is a tough craft, writing great documentation is an art. So sadly this is somewhat expected. Yet I’ll try now and then…
If your only option is RHEL, no.
If I’ll find one, I’ll delete it.