Issue title: Walkthrough Step 9: Component Configuration Documentation is missing index.js
 Issue body: OpenUI5 version: 1.61.2

Browser/version (+device/version): Chrome/72.0.3626.81 (macOS 10.13.6 (17G4015))

Any other tested browsers/devices(OK/FAIL):
FAIL Firefox 62.0b20 (64 bits)

URL (minimal example if possible): [Step 9: Component Configuration](https://openui5.hana.ondemand.com/#/topic/4cfa60872dca462cb87148ccd0d948ee)

User/password (if required and possible - do not post any confidential information here):

Steps to reproduce the problem:
1. Open Step 9
2. Download step files and decompress
3. Adjust bootstrapping code inside index.html if needed
3. Open webserver in webapp folder (I am using python -m http.server NNNN for this example)
3. Load app in browser: localhost:NNNN

What is the expected result?
Load index.js
Documented step in walk-through detailing changes in index.js

What happens instead?
Error while trying to load index.js (browser's console)
index.js from previous step does not work

Any other information? (attach screenshot if possible)

Probably related to #2338

The tutorial says the index.js file is not needed any more:

> Since the Component.js now handles everything, we no longer need our index.js.

However, there is no connection between the html file and the application. That means the html still references to index.js when loading the bootstrap:

`data-sap-ui-oninit="module:sap/ui/demo/walkthrough/index"`

Moreover, when reviewing the [app code](https://openui5.hana.ondemand.com/test-resources/sap/m/demokit/tutorial/walkthrough/09/webapp/index.html), index.js was properly updated to reflect the changes from the XMLView to the ComponentContainer.

```
sap.ui.define([
	"sap/ui/core/ComponentContainer"
], function (ComponentContainer) {
	"use strict";
	new ComponentContainer({
		name: "sap.ui.demo.walkthrough",
		settings : {
			id : "walkthrough"
		}
	}).placeAt("content");
});
```

![capture d ecran 2019-02-07 a 19 02 49](https://user-images.githubusercontent.com/1663486/52450897-fca74a00-2b0a-11e9-8162-607df2d5afca.png)
 Comments: 
 Comment 0: Hello @arguapacha,

thank you for reporting this, we missed out to add the index.js file to the documentaiton, it was only available in the code. We updated the documentation accordingly:
https://openui5nightly.hana.ondemand.com/#/topic/4cfa60872dca462cb87148ccd0d948ee

All the best,
Michael
{'source': 'GithubIssues', 'repo_name_with_owner': 'SAP/openui5', 'issue_id': 407952569, 'repo_stars': 2981.0}