Add initial run local instructions to readme

website/README.md

@@ -7,3 +7,20 @@ 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.
+
+## Previewing Changes
+
+You should preview all of your changes locally before creating a pull request. The build includes content from this repository and the `terraform-website` repository, allowing you to preview the entire Terraform documentation site.
+
+**Set Up Local Environment**
+
+1. [Install Docker](https://docs.docker.com/get-docker/).
+2. Create a ~/go directory manually or by [installing Go](https://golang.org/doc/install).
+3. Set GOPATH as an environment variable: 
+  - bash: `export $GOPATH=~/go`
+  - zsh: `echo -n 'export GOPATH=~/go' >> ~/.zshrc`
+4. Restart your terminal or command line session.
+
+**Launch Site Locally**
+
+Navigate into your local `terraform` top-level directory and run `make website`. Preview the site at http://localhost:4567.