The Street Complete supports that as well - you can add a note with an (optional) picture and many of the "quests" have that option as well. In the past I have

The Street Complete supports that as well - you can add a note with an (optional) picture and many of the "quests" have that option as well. In the past I have created a few of those ("gate is no longer there"/"way is blocked by trees", "there is a new ATM at this spot") and some of them have already been addressed (you get an email when it happens).