Add a minimal README

- #128

README.md

@@ -0,0 +1,21 @@
+# Development
+
+## Dependencies
+
+Make sure that you have `node` >= 14 and `npm` >= 7. Node 14 ships with npm v6,
+so if you're using node 14, you would need to upgrade npm. Alternatively you
+could also upgrade to node 16, which ships with npm 7.
+
+How to upgrade npm: `npm i -g npm`
+
+## Local
+
+- `npm install` to install project dependencies
+- `npm run dev` to run the dev server (http://localhost:3000)
+
+## Production
+
+- `npm install` to install project dependencies
+- `npm run build` to generate html/css/js
+- `npm run export` to move the built files (along with assets in the public directory) to the `/out` directory
+- Use your favourite web server to host the files in the `/out` directory. (A very simple one would be `python -m http.server` - not sure if it should actually be used for production :P)