It was a nice surprise.
If anyone wants to knows how to get there (there's tons of gravestones with messages from the devs etc.), when you enter Haven, the graves are behind the first house on the right (use TAB to see them). Facing the house, on the right side there's an small cap on the edge of the fence from where to enter the graveyard.
Not sure if you need to complete the Sacred Ashes quest first and then return to Haven for this to work, I found them after doing the quest.