fine-tune README.md

Author: rwieruch

README.md

@@ -54,7 +54,8 @@ If you are creating an open source application under a license compatible with t
 
 ### Firebase Configuration
 
-* visit https://firebase.google.com and create a Firebase App
+Get an overview of Firebase, how to create a project, what kind of features Firebase offers, and how to navigate through the Firebase project dashboard in this [visual tutorial for Firebase](https://www.robinwieruch.de/firebase-tutorial/).
+
 * copy/paste your configuration from your Firebase project's dashboard into one of these files
   * *src/components/Firebase/firebase.js* file
   * *.env* file