Update README.md

Update the readme to also instruct the user to remove the `let` keyword in data/appConfig.js

README.md

@@ -40,8 +40,8 @@ the container please moint a volume in ``/var/www/html/data/``
 
 # Config
 You can configure the visualization frontend via ``appConfig.js``
-copy the ``/js/appConfig.example.js`` into ``/data/appConfig.js`` (where your volume should be mounted)
-
+copy the ``/js/appConfig.example.js`` into ``/data/appConfig.js`` (where your volume should be mounted).
+Change ``let appConfig = {`` to ``appConfig = {`` in /data/appConfig.js
 
 #### Libs used
 1. Bootstrap 4 - alpha