It's in the works. The plan is to have the primary pkgdown site with the documentation for the latest CRAN release of a package, and a dev. site with the documentation for the package in development (not indexed for search, etc.) – so, basically, you, “a user not at all familiar with the…development process”, won't be led astray by peeks of what's in the pipeline in outside of the CRAN version.
We're working out the process atm (them's the breaks of FOSS, since pkgdown is, itself, in active development), but Jenny has a system running for usethis you can take a look at (screenshots of the reference page, bc index has installation instructions for CRAN and devtools, which might change):
CRAN usethis http://usethis.r-lib.org/index.html
dev usethis http://usethis.r-lib.org/dev/index.html
Currently there isn't an easy way to navigate between them without knowing the URL, due to the fact that things only got this far two days ago: