I left 18 months ago, so my memory is a bit fuzzy, but there was at least an overall style guide, one for each post type (e.g. a launch announcement), and the style for procedures (inherited from AWS Docs).

Oh, I was being facetious. I'm pretty sure Jeff mentioned needing to spend time writing a style guide when he started having other Amazonians write posts for "his" blog.

As a non-Amazonian I've never seen it, of course.