Scaladoc page/link improvements

[reibitto]

Right now the link to the scaladocs page is a little strange:

• If you compare the ZIO scaladocs with zio-process, you'll notice the top bar is missing (where you have the download link, switch between 2.12/2.13, etc):
  https://javadoc.io/doc/dev.zio/zio_2.12/latest/index.html
  https://zio.github.io/zio-process/api/index.html
• Also, both ZIO and zio-process have this issue so not sure it can be changed, but the default view is the root package. I don't think this is too helpful. Is it possible to change it? For example, ideally I think the zio-process scaladocs should link to the zio.process namespace like:
  https://zio.github.io/zio-process/api/zio/process/index.html