travis: attempt to build docs on CI
travis: attempt to build docs on CI

peterbarker/dronekit-la,peterbarker/dronekit-la,peterbarker/dronekit-la,dronekit/dronekit-la,peterbarker/dronekit-la,dronekit/dronekit-la,dronekit/dronekit-la,dronekit/dronekit-la