add instructions for using prebid as npm depenedency added to readme

Author: snapwich

README.md

@@ -16,11 +16,94 @@ Working examples can be found in [the developer docs](http://prebid.org/dev-docs
 
 **Table of Contents**
 
+- [Usage](#Usage)
 - [Install](#Install)
 - [Build](#Build)
 - [Run](#Run)
 - [Contribute](#Contribute)
 
+<a name="Usage"></a>
+
+## Usage (as a npm dependency)
+
+*Note:* Requires Prebid.js v1.38.0+
+
+Prebid.js depends on Babel and some Babel Plugins in order to run correctly in the browser.  Here are some examples for 
+configuring webpack to work with Prebid.js.
+
+With Babel 7:
+```javascript
+// webpack.conf.js
+let path = require('path');
+module.exports = {
+  mode: 'production',
+  module: {
+    rules: [
+      
+      // this rule can be excluded if you don't require babel-loader for your other application files
+      {
+        test: /\.m?js$/,
+        exclude: /node_modules/,
+        use: {
+          loader: 'babel-loader',
+        }
+      },
+      
+      // this separate rule is required to make sure that the Prebid.js files are babel-ified.  this rule will
+      // override the regular exclusion from above (for being inside node_modules).
+      {
+        test: /.js$/,
+        include: new RegExp(`\\${path.sep}prebid\.js`),
+        use: {
+          loader: 'babel-loader',
+          // presets and plugins for Prebid.js must be manually specified separate from your other babel rule.
+          // this can be accomplished by requiring prebid's .babelrc.js file (requires Babel 7 and Node v8.9.0+)
+          options: require('prebid.js/.babelrc.js')
+        }
+      }
+    ]
+  }
+}
+```
+
+Or for Babel 6 and/or Node v8.6.0 and less:
+```javascript
+            // you must manually install and specify the presets and plugins yourself
+            options: {
+              plugins: [
+                "transform-object-assign", // required (for IE support) and "babel-plugin-transform-object-assign" 
+                                           // must be installed as part of your package.
+                require('prebid.js/plugins/pbjsGlobals.js') // required!
+              ],
+              presets: [
+                ["env", {                 // you can use other presets if you wish.
+                  "targets": {            // this example is using "babel-presets-env", which must be installed if you
+                    "browsers": [         // follow this example.
+                      ... // your browser targets. they should probably match the targets you're using for the rest 
+                          // of your application
+                    ]
+                  }
+                }]
+              ]
+            }
+```
+
+Then you can use Prebid.js as any other npm depedendency
+
+```javascript
+import prebid from 'prebid.js';
+import 'prebid.js/modules/rubiconBidAdapter'; // imported modules will register themselves automatically with prebid
+import 'prebid.js/modules/appnexusBidAdapter';
+prebid.processQueue();  // required to process existing pbjs.queue blocks and setup any further pbjs.queue execution
+
+prebid.requestBids({
+  ...
+})
+
+```
+
+
+
 <a name="Install"></a>
 
 ## Install