We missed this one on a previous pass of bringing in most of the cty
stdlib functions.
This will resolve#17625 by allowing conversion from Terraform's
conventional RFC 3339 timestamps into various other formats.
This commit is a wide-ranging set of edits to the pages under
/docs/configuration. Among other things, it
- Separates style conventions out into their own page.
- Separates type constraints and conversion info into their own page.
- Conflates similar complex types a little more freely, since the distinction is
only relevant when restricting inputs for a reusable module or resource.
- Clarifies several concepts that confused me during edits.