add a donation info for OSM Foundation and Overpass

[riccardoklinger]

https://wiki.osmfoundation.org/wiki/Donate

the donations ffor overpass is still under discussion: tyrasd/overpass-turbo#397

[mmd-osm]

Overpass turbo is the web frontend in this case.,Overpass API, the database backend with the big servers, is sponsored by FOSSGIS e.V. which is also the local OSM chapter in Germany.

https://www.fossgis.de/wiki/F%C3%B6rderantr%C3%A4ge/Overpass-Erweiterung