docs: catches the case whereby assets are an object (#311)

* updates example - catches the case whereby assets are an object

* Update README.md

correct typecheck in SSR example

* Update README.md

uses helper for isObject

Author: soaringeagle

README.md

@@ -314,10 +314,14 @@ Example Implementation:
 ```js
 const webpack = require('webpack');
 const compiler = webpack({ ... });
+const isObject = require('is-object');
 const middleware = require('webpack-dev-middleware');
 
 // This function makes server rendering of asset references consistent with different webpack chunk/entry configurations
 function normalizeAssets(assets) {
+  if (isObject(assets)) {
+    return Object.values(assets)
+  }
   return Array.isArray(assets) ? assets : [assets]
 }