Provide a mechanism for error reporting

[Daniel-Mietchen]

I just had an image of a river bank that the guessr's map had located 4km away from that river bank.
It would be good if there were an option to go and fix the underlying items - perhaps after the guessing step and before moving on to the next image.

It would also be useful to have some more explanation of how the distances and scores are calculated - if Wikidata has only one geolocation for a city, then most images from within that city will always be off a bit, unless the task is clarified to something like "pinpoint the center of the closest administrative unit" or so.