consider having a release and dev version of the pkgdown website

[cjyetman]

As the r2dii packages do, it's possible to automatically maintain two pkgdown websites, one for the "release" version (generated at the root level of the pkgdown website whenever a standard semantic version number is used in the DESCRIPTION) and a "dev" version for whatever is on main whenever a version number has four components, e.g. 0.0.0.9000

how-to documented here: https://pkgdown.r-lib.org/reference/build_site.html#development-mode