Add OSM contribution tag line to our main map

Description

Our main map https://foodsharing.de/karte is missing a contribution tag line as e.g. visible on https://foodsharing.de/?page=settings&sub=general

It also seems to be visible on iOS

Goal

Give credits to OSM. Follow the licensing rules of OSM.

Solution

add tagline via leaflet or find a new map vue wrapper which offers such a tagline.

Links / references

OSM copyright: https://www.openstreetmap.org/copyright

Example of such usage: https://www.openstreetmap.org/#map=15/51.0103/13.6608