refactor: Add minimal terraform project (#308)

I was thinking it might be nice to have some example projects (especially as we on-board new developers) to make it easy to create new projects.

This adds the most basic possible terraform module... just an output block. However, it's enough to run `coder projects create` and go through the whole lifecycle of creating a project and workspace (although, it's really boring since there are no parameters).

README.md

@@ -10,7 +10,8 @@ This repository contains source code for Coder V2. Additional documentation:
 ## Directory Structure
 
 - `.github/`: Settings for [Dependabot for updating dependencies](https://docs.github.com/en/code-security/supply-chain-security/customizing-dependency-updates) and [build/deploy pipelines with GitHub Actions](https://docs.github.com/en/actions/reference/workflow-syntax-for-github-actions).
-  - [`semantic.yaml`](./github/semantic.yaml): Configuration for [semantic pull requests](https://github.com/apps/semantic-pull-requests)
+  - [`semantic.yaml`](./github/semantic.yaml): Configuration for [semantic pull requests](https://github.com/apps/semantic-pull-requests)\
+- `examples`: Example terraform project templates.
 - `site`: Front-end UI code.
 
 ## Development

examples/minimal-project/main.tf

@@ -0,0 +1,4 @@
+# The simplest possible Terraform module: it just outputs "Hello, World!"
+output "hello_world" {
+  value = "Hello, World!"
+}