post https://api.foursquare.com/v2/venues//flag
Allows users to indicate a venue is incorrect in some way.
Note: Flags are pushed into a moderation queue. If a closed flag is approved, the venue will no longer show up in search results. Moderators will attempt to correct cases of mislocated or duplicate venues as appropriate. If the user has the correct address for a mislocated venue, use proposeedit instead.