Add devcontainer setup

It will make contributions easier by allowing people
to get it working locally with one click or to bring
it up in github codespace.

.devcontainer/Dockerfile

@@ -0,0 +1,5 @@
+FROM node:latest
+
+WORKDIR /site
+
+CMD ["npm", "run serve"]

.devcontainer/devcontainer.json

@@ -0,0 +1,8 @@
+{
+  "name": "Npm setup for building the turbo site",
+  "build": {
+    "dockerfile": "Dockerfile"
+  },
+  "postCreateCommand": "npm install",
+  "postStartCommand": "npm run serve"
+}

README.md

@@ -4,10 +4,18 @@ This repository backs the website living at https://turbo.hotwired.dev.
 
 To work on it locally:
 
+## Option A: Directly on your machine
+
 1. `npm install`
 2. `npm run serve`
 3.  (If you need it: `npm install markdown-it` and rerun step #2).
 
+## Option B: Using a devcontainer
+
+There is a devcontainer configuration that, when started, will perform all of the setup and serve the website on port 8080.
+
+For example, in VSCode, run "Reopen in Container" and wait for it to finish and access the site on http://localhost:8080/,
+
 ## Copyright
 
 The logo, design, and other aesthetic parts of this website is copyright 37signals, all rights reserved. Feel free to be inspired by the structure, but do not copy the specific design, anymore than you'd copy basecamp.com or hey.com.