Document the `path` configuration for environments

[linhr]

In the Environment configuration page, it says:

The storage location for environments is completely configurable.

The "storage location" link points to the page for global Hatch configuration (config.toml). It is unclear that the environment location can actually be configured on a per-environment basis via path. I learned about this only after looking at related issues such as #889.

Can we add a note to the documentation if path is a publicly supported environment configuration?

[dbrtly]

An explicit statement that config.toml is a global config would help alot. That confused me. I thought it was supposed to be added to the project not the machine.