The blog is a good place for material that feels more narrative than procedural. If the docs explain how to use something, the blog can explain why a decision was made or how the product is evolving.
A practical rule
If the page needs a sidebar, a table of contents, and a strict order of steps, it probably belongs in the docs.
If the page is better served by a short introduction, a few headings, and a date stamp, it probably belongs here.
Keep it lightweight
The first version of the blog does not need tags, search, or complex editorial workflow. Starting with a handful of markdown files makes the content model obvious and keeps the site easy to maintain.