I've also found that it's more useful to use a good doc as an outline for your own documentation than to start from scratch + style guide. Using a good doc as a guide can help you develop your own documentation style – you can figure out what works and doesn't work for you.

Style guides can be great in the right context, but I think focusing on them too much can take away from the most important part of documentation – the content.

That being said, Microsoft and Google have decent, publicly-available tech writing style guides: -Microsoft: https://docs.microsoft.com/en-us/style-guide/acronyms -Google: https://developers.google.com/style