Update reference.mdown
Update reference.mdown

Bad links were resulting in 404. They were linking as if this document were in root, but it's not :)
stitchfix/stateface,propublica/stateface,Skoks/stateface,veltman/stateface,Skoks/stateface,veltman/stateface,Skoks/stateface,stitchfix/stateface,propublica/stateface,veltman/stateface,propublica/stateface