Update README

Add useful information and how to setup/test.

Author: coderkevin

README.md

@@ -1,2 +1,24 @@
-# woocommerce-product-inventory-datastore
-Sample WooCommerce DataStore for products, overrides inventory count
+# Demo Inventory Data Store for WooCommerce Products
+
+This demo shows an example of how to extend existing Data Stores in WooCommerce.
+
+**NOTE: This is demo code and not even close to being something you want to use in production.**
+
+It extends an existing Product Data Store, and overrides only the inventory count,
+replacing the database count with one retrieved from an external API.
+
+## Try it out!
+
+This plugin has everything needed to try out the example code.
+
+### Pre-Setup
+
+1. Set up a test WooCommerce site.
+2. Add 3 products with SKUs of "p120", "p121", and "p122", set stock quantities.
+
+### Plugin Setup
+
+1. Clone this repository under `wp-content/plugins`.
+2. Under the `server` directory run `npm install` then `npm start` to run the test API server.
+3. Activate the "WooCommerce Product Inventory Datastore" plugin.
+4. Observe the products with the SKUs above now receive inventory counts from the API instead of `wpdb`.