Add screenshots to introduction

[herbertblb]

@seragarez, would you prepare screenshots of the final states?
I then can try to include them (I do not know how it works though, but I will try to find out)

[seragarez]

Yes, will do that! But I am still waiting in case further changes are coming.. until when do you think you need them at the latest?

[herbertblb]

around 5 maybe

[herbertblb]

also, when I open the app, the time slider is blue, is that how it´s supposed to be @erictapen ? Because in the screenshot on Miro it´s grey

[erictapen]

@herbertblb The screenshot of the timeslider is a non-decision yet unfortunately... Never really looked into how it could be styled.
So if its greyscale on some images that should be solely due to browser-dependent behaviour.