Dev docs should be deployed at GitHub pages root

[gadenbuie]

I noticed today that https://posit-dev.github.io/py-shiny gives a 404 because the site is at https://posit-dev.github.io/py-shiny/docs.

If we don't have a reason for needing the subdirectory, it'd be preferable to deploy to the github pages root (preferable in the sense of me remembering the url without having to look it up).