docs: document build and start scripts

Issue #47

README.md

@@ -99,3 +99,28 @@ The chunks would be written out as:
   }
 </script>
 ```
+
+# Modifications
+
+## Building
+
+Building is done via webpack as a universal module definition (UMD) library.
+
+From terminal
+
+```bash
+npm run build
+```
+
+1. Creates a script in development mode under /docs/dist/riff-wave-reader.js
+1. Creates a script in production mode under /lib/dist/riff-wave-reader.js along with a sourcemap file
+
+## Local Testing
+
+From terminal
+
+```bash
+npm run start
+```
+
+Your web browser will open http://localhost:3000/docs/index.html