Add info box to interactive maps

[tjukanovt]

The methodology behind the analyses might seem complex to new users. As a user I would like to have an info box on the maps to have some basic information on how the analyses are made.

Describe alternatives you've considered
This service has nice and simple info boxes embedded on the interactive map. The solution could be very similar.

Additional context
The info box should also contain information about the licenses of source data: #16