It matters how big your guide will be. Just some Markdown? Github Gist. A few Markdown files? Gist/ Repository. A large-scale documentation? Use Github Pages.
Hope this helps
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I just deleted my Reddit account and will delete my Twitter too as soon as I get my data export.
Unfortunately, I'll have to wait for Instagram, Facebook & WhatsApp until most people I know will move to a Fediverse alternative too.