Add missing website information / remove unused configuration

[johnjohndoe]

• It became obvious in the last OKLab Berlin meetup when @jochenklar and @k-nut presented the project that essential information about the project are missing.
• Remove references and icons from Wo ist Markt?
• The icons need to be replaced and re-added here. :warning:
• Remove unused deployment and CI configuration from Wo ist Markt?

[joergreichert]

Thanks for your contribution. Merged it. Maybe we need to put the links also into the upper menu bar next to the burger menu (maybe as a question mark symbol) so they would be more visible than with small font in map footer.