...and also shrink the explanation for alternate sharing approaches, a bit.
Actually, it looks like I already half-adopted it by accident. 😬 But this
commit adds it to the sidebar under "State", so users can browse to it. I'm
leaving the URL alone, because it's not urgent and we'll need to adjust a large
swath of URLs at some point anyway.
This change effectively stops presenting `terraform` as a provider in the normal
sense, and reduces /docs/providers/terraform/index.html to a ghost page in the
language section (to avoid breaking links for the time being). The message a
reader should get is that Terraform has one special built-in data source where
you don't need to think about the provider or its version.
5ceb8b2b98