The demo is the product

Every good technical product has a moment where the reader stops reading and starts poking. The entire job of a project page is to get to that moment as fast as possible and then get out of the way.

Most fail by explaining first. Seven screens of context, an architecture diagram, a paragraph about the team's philosophy — and then, below the fold, a thing you could have clicked immediately. The explanation was written for the author, who already understands it, rather than the reader, who does not yet care.

Inverting it is uncomfortable, because putting the interactive thing first means it has to survive contact with someone who has no context. Which is the point. If it cannot, the explanation was load-bearing, and that is a product problem wearing a documentation costume.

The test is simple: hand it to someone and say nothing. Whatever they do first is your real interface. Whatever they ask first is your real documentation. Everything else is you talking to yourself.