Improve documentation

Makefile

@@ -1,2 +1,8 @@
-build:
+build-rust:
 	wasm-pack build --target=web
+
+build-ui:
+	rm -rf ui/dist ui/.parcel-cache
+	cd ui; npm run build
+
+build-all: build-rust build-ui

README.md

@@ -0,0 +1,22 @@
+# README
+
+This repository contains the code for 'WordGrid', a (currently) single-player browser game where you use letter tiles to form words.
+
+Game logic resides in `src/` as Rust code, which gets compiled into WebAssembly. 
+
+UI logic resides in `ui/src/`, which gets bundled by Parcel into the web application.
+
+## Setup
+
+* Make sure you have [Node.js](https://nodejs.org/en) installed and [rustup and Cargo](https://www.rust-lang.org/learn/get-started).
+
+1. Clone this repository.
+2. If not already installed, install the Rust `wasm32-unknown-unknown` target with `rustup target add wasm32-unknown-unknown`.
+3. In the base project directory, run `make build-all` to build both the Rust wasm project (gets stored in `pkg/`) and the final bundled web files (gets stored in `ui/dist/`). 
+4. Place the files in `ui/dist/` onto a web server and access them.
+
+During development, you'll often want to serve the UI component in serve mode that auto-updates when you make a change. In the `ui/` directory you can run `npm run start`. Note that Parcel doesn't always detect changes to the compiled Rust code, so if you recompile the Rust code with changes you should delete `ui/.parcel-cache/` and `ui/dist/` or else the UI may continue to use older WASM. 
+
+## Future Plans
+
+I intend on building a multiplayer component to this game, where the Rust code will form a webserver for connecting players and the UI will make server calls instead of calling web assembly.