We previously had some notes about handling configuration variants just
tacked on to the "dependency inversion" section as an afterthought, but
this idea is a major use-case for dependency inversion so it deserves its
own section and a specific example.
We have released the v0.12-oriented content to the website early in order
to support the beta process, but in some places we neglected to explicitly
mark features or content as being v0.12-only.
Here we add explicit markers to the main cases we've seen where readers
have reported confusion, along with some other tweaks in similar vein.
As well as some general consolidation and reorganizing, this also includes
some updated advice for making the best use of new Terraform v0.12
features to create infrastructure building-blocks.
In particular, the "Module Usage" documentation is now consolidated into
the configuration section in order to bring all of our general language
documentation together, and the top-level "Modules" section is now
primarily focused on module _authors_ as an audience, covering topics such
as publishing modules and designing them for reuse.
Martin Atkins