feat: support auto-documentation of Meltano `Environments`

[kgpayne]

MVP might be to simply have a docs page listing the environments and their env vars. We may also choose to link to the plugins referenced in the environment.

[kgpayne]

@edgarrmondragon I wonder if it might be worth adding label and description attributes to the Environment entity, so that users can document intended usage of their environments in YAML for sphinx-meltano to render in the docsite. WDYT?

[edgarrmondragon]

@kgpayne sounds like a good idea to me

[aaronsteers]

@edgarrmondragon I wonder if it might be worth adding label and description attributes to the Environment entity, so that users can document intended usage of their environments in YAML for sphinx-meltano to render in the docsite. WDYT?

It might be worth a pass off the JSON schema all-up. Any major Meltano entities that don't yet have declared support for description (sentence format descriptions) or label (title case for "name", with spaces and special characters allowed) should probably be evaluated for supporting those attributes.

Entity types that come to mind which might similarly benefit: plugins, jobs, schedules, environments, and commands.