Added README for types module.
Added README for types module.

cramja/incubator-quickstep,hbdeshmukh/incubator-quickstep,tarunbansal/incubator-quickstep,zuyu/incubator-quickstep,zuyu/incubator-quickstep,hbdeshmukh/incubator-quickstep,UWQuickstep/quickstep,tarunbansal/incubator-quickstep,zuyu/incubator-quickstep,jianqiao/incubator-quickstep,UWQuickstep/quickstep,tarunbansal/incubator-quickstep,hbdeshmukh/incubator-quickstep,tarunbansal/incubator-quickstep,UWQuickstep/quickstep,jianqiao/incubator-quickstep,jianqiao/incubator-quickstep,cramja/incubator-quickstep,cramja/incubator-quickstep,UWQuickstep/quickstep,cramja/incubator-quickstep,jianqiao/incubator-quickstep,zuyu/incubator-quickstep,hbdeshmukh/incubator-quickstep,UWQuickstep/quickstep