docs(scully): put link to set up angular project & note needed chromium support

* docs: put a link to set up an angular project 

make it easier for beginners to start with

* docs(scully): chromium support by OS is required

on some systems, like mine, you can't use chromium

Author: willi84

docs/getting-started.md

@@ -1,6 +1,10 @@
 # Scully - Getting Started
 
-The first thing you need to get started with Scully is a working Angular app using **Angular 9.x.x**
+## Prerequisites 
+The first thing you need to get started with Scully is a working Angular app using **Angular 9.x.x**.
+Find more infos here ([👉 angular.io/cli](https://angular.io/cli)
+
+__NOTE:__  Scully will use Chromium. Make sure your Operating System (and its restrictions by your administrator) allow installing and executing Chromium. 
 
 This getting started doc covers the three steps to adding Scully into your project.