Documentation Tools for Small Shops

I'm curious what documentation tools exist that would be suitable for a small IT operation because I'm outgrowing my current solution.

I'm a solopreneur and self support but in a sense identify with the sysadmin community (more so than, *e.g.*, the homelab community) because I administer two production Linux servers, a Linux firewall, three Linux desktops, and several Windows and Mac machines both physical and virtual.

My current IT documentation solution is a set of word processing documents, which have the advantage of indexing, outlining, and native cross-referencing, all with hyperlinks, not to mention ease of use.

These documents have grown to be unwieldy and slow. The solution has been to calve off this section or that but this comes at the cost of lost cross-referencing and hyperlinking across the documents.

So, the question is what other solutions might exist, what others' experience has been with them, and what others might recommend.

I'm perfectly comfortable with complex implementations but easy wins every time. So, for example, I don't necessarily want to have to configure an entire LEMP stack just to look up an iptables module I coded. I can and will if that makes sense but it's a consideration. Some organization or outlining capability and hyperlinking are key. Editing in the document would be a plus. The flexibility to extend into generalized knowledge management would be very nice to have. FOSS is good, as is adoption, an installed base, and active development.

Things I'm toying with include:

* Various wiki software * Texinfo * Straight-up XML * WordPress, although implementations start looking like wikis.

Note takers and PIMs obviously aren't sufficiently robust. I coded up a Zettelkasten (note card file) a while back in MS Access and it's okay but not fabulous notwithstanding some neat tricks. The hyperlinking in word processing documents works much better, at least for this use case. CHM format is interesting somewhat but deprecated.

Of course, I also could be barking up the wrong trees entirely.

Thanks for any thoughts.