What I've ended up doing is to just write Word documents containing what I do. I keep my Word documents in a single directory on my OneDrive, so I can access them on all my machines.
Raspberry Pi iSCSI server? One document for that, containing the links to guides used, commands I've run and scripts made. I use headers to organize the sections, like one for compiling the custom kernel, one for configuring iSCSI on the Pi, one for using it on the NAS etc.
Need to create a new Docker SMB mount? Once the right incantation has been found, a small script is made and also added to the right Word document, ready to be pasted into the next machine I might need it on.
It's not terribly pretty and not at all fancy, but I found it's low enough barrier that it's easy to do and maintain, and it's very helpful to have it all in one place.
Had I been a Linux guy first and foremost I would probably have used something else than Word, but it works and I find the separation between the regular font for comments and monospace for script makes it easy to quickly distinguish. It's also easy to add screenshots for clarifications etc.