add nominatim docker example

This setup works for me. There are still some things missing:

• keep data up-to-date after initial import
• move this to a more suitable place, e.g. docs
• disable rate limiting (not necessary for self hosted instance)

Initial setup (~20min):

mkdir nominatim
wget 'https://download.geofabrik.de/europe/germany/berlin-latest.osm.pbf' -O nominatim/berlin.osm.pbf
docker-compose run --rm nominatim sh /app/init.sh /data/berlin.osm.pbf postgresdata 4
rm nominatim/berlin.osm.pbf

Example query:

curl 'http://localhost:7070/search?city=berlin&country=germany&street=Lentzeallee%2094&limit=1&format=json'

Sources:

• https://hub.docker.com/r/mediagis/nominatim
• https://download.geofabrik.de/europe/germany/berlin.html
• https://nominatim.org/release-docs/latest/admin/Import-and-Update/