Adds document about metrics being tracked
Adds document about metrics being tracked

CartoDB/Windshaft,HydroLogic/Windshaft,CartoDB/Windshaft,CartoDB/Windshaft,manueltimita/Windshaft,manueltimita/Windshaft,wsw0108/Windshaft,wsw0108/Windshaft,wsw0108/Windshaft,HydroLogic/Windshaft,HydroLogic/Windshaft,manueltimita/Windshaft