I would suggest to take a look at MarkDown, or even better AsciiDoc.
Both have visually oriented editors available (freeware or open source), which enable you to edit and create new documentation in them. It is easy enough to pick up.
Now I think that the syntax and logic behind AsciiDoc are a vast improvement over MarkDown, but for the latter there are more editors available and a lot of websites support it nowadays.
After explaining my bias, for creation of AsciiDoc documentation I prefer the AsciiDocFX editor. For editing existing documents, VSCode is preferable when you work with documentation that is managed by Git or other version control systems.
With a bit of forethought about how you want to structure your files, images etc. you can then easily link to files, media, images etc. using relative paths (or absolute), but also to different documents or sections thereof. AsciiDocFX has a pretty descriptive cheat sheet built-in and most layout options are available as menu option, one or two mouse clicks away.
The main problem from AsciiDoc or MarkDown for that matter, none of the editors have a GUI interface that is as familiar as Word. But an AsciiDoc document is text-based, very human readable in raw format and can be easily converted into PDF, HTML5 or eBook formats. AsciiDocFX has these already built-in. The HTML output can be imported into Word without any problem. And then you can even store the imported document in the native Word format, if that is a solid requirement.
Because AsciiDoc and MarkDown are text-based formats, you can use almost any text editor to open these documents. This makes it also very easy to index such documentation by any type of search software on any operating system.
If the above is too much of a mindset deviation, there is another way. Though it does require you to have an online website/blog from a 3rd party. Then you could use a piece of software called: open livewriter
You have to hook it up to 1 or more of these 3rd party services during the installation procedure, but then you get a Wordpad-like editor that stores the documents you create with it directly onto the configured 3rd party service(s). Then you could consider to use the google search engine for searching your documentation.
Still, I would take the time to get acquainted with AsciiDoc, not the easiest option in the beginning, but once you "get" it I think it is the best option. After you made several documents using AsciiDoc, you could even use the Hugo web server software to generate static HTML pages from these documents and the Hugo results you can host (directly) on a local website or one you purchase from a 3rd party. Whatever tickles you.
AsciiDocFX has a spell-checker built-in. While not as extensive as the one from Word, it is pretty capable. And supports more than one language, right out of the box.
So, if you are not hell bent on a Word-like GUI or it's file format, AsciiDoc is much more future-proof, because it's syntax is less convoluted then MarkDown and text based, so it works the same on any edition/version of Windows in existence...or other operating systems like Linux, MacOS and/or BSD.
