Updated universal browser example readme (#1252)

Author: matux

examples/universal-browser/README.md

@@ -1,5 +1,20 @@
-- npm install
-- npm start
+# Universal Browser Example
 
-This only uses a server to get around CORS for loading the rollbar library from a local file via the
-snippet.
+This example demonstrates using Rollbar.js with the async snippet pattern in a browser environment.
+
+## Setup
+
+```bash
+npm install
+npm start
+```
+
+## Usage
+
+Visit http://localhost:3000/test to see the example in action.
+
+## How it works
+
+- Uses the Rollbar snippet to asynchronously load the library
+- Includes a test server to avoid CORS issues when loading local files
+- Demonstrates error capture when clicking buttons that call undefined functions