State maintained by the Julia Package Ststem

The Julia Package system maintains various loci of state for each package. The ones I can think of off the top of my head are

  • the General registry on GitHub
  • the user’s local copy of the General registry in .julia/registries/General
  • user registries both locally and on GitHub
  • local copies of each package under .julia/packages
  • packages in .julia/dev
  • the Project.toml and Manifest.toml file in each local package directory

There re various functions and commands in Pkg. It would be helpful if there were documentation describing the purpose/use of each of thes loci and how the various functions and commands alter this state.

Is there such documentation? Can anyone enlighten me?