Docs: finish implementing Terraform Docs templates

[mitchnielsen]

Summary

We use https://github.com/hashicorp/terraform-plugin-docs to generate docs, but currently we only use it for the Block resource docs. Let's finish implementing it for the rest of the resources to DRY things up and ensure any changed metadata/schema will be automatically updated in the docs as part of pre-commit/CI.

Acceptance criteria

• All resources and datasources use terraform-plugin-docs