The entire front page is actually powered by a very old, customised version of XF. The back end of that has a system which is (again custom built), I guess, similar to the help page system in XF right now, though it supports a tree structure similar to the node system. The front end clearly uses a different style entirely from the forum one.
If you're looking for a way to create documentation/manuals, you might be better off looking at something like a "static document generator" rather than a fancy script.
For example, two which come to mind are Sphinx and MkDocs. Both of these are built using Python, but aside from installing it locally there's not really a great deal to get involved with there. Once it's installed, your documentation layout will be configured with a somewhat simple configuration file, and your documents themselves will be written with something like Markdown or reStructuredText - no HTML and no coding required. Both of the above have built in and third party themes which are easily customisable.
Once the documentation is built it is written out to basically static HTML files which you then upload to your location of choice or have it hosted on somewhere like GitHub pages, or a service for hosting documentation like "Read the docs".
