website: A note about where the root parts of the website live now

website/README.md

@@ -0,0 +1,9 @@
+# Terraform Documentation
+
+This directory contains the portions of [the Terraform website](https://www.terraform.io/) that pertain to the
+core functionality, excluding providers and the overall configuration.
+
+The files in this directory are intended to be used in conjunction with
+[the `terraform-website` repository](https://github.com/hashicorp/terraform-website), which brings all of the
+different documentation sources together and contains the scripts for testing and building the site as
+a whole.