Add docs about the webpack approach

README.md

@@ -14,6 +14,7 @@ For Documentation, visit <https://caolan.github.io/async/>
 
 *For Async v1.5.x documentation, go [HERE](https://github.com/caolan/async/blob/v1.5.2/README.md)*
 
+## Usage
 
 ```javascript
 // for use with Node-style callbacks...
@@ -48,3 +49,23 @@ async.mapLimit(urls, 5, async function(url) {
     console.log(results)
 })
 ```
+
+## Usage in browser with webpack
+
+To keep the bundle as small as possible, don’t import the whole library. Import only methods you use instead.
+
+```javascript
+// ❌ DON’T: 
+import async from 'async';
+async.mapLimit(urls, 5, async function(url) {
+    const response = await fetch(url)
+    return response.body
+})
+
+// ✔ DO:
+import { mapLimit } from 'async';
+mapLimit(urls, 5, async function(url) {
+    const response = await fetch(url)
+    return response.body
+})
+```