Adding docstring example for addW2Layer
Adding docstring example for addW2Layer

chhao91/pysal,lixun910/pysal,ljwolf/pysal,ljwolf/pysal,ljwolf/pysal_core,sjsrey/pysal_core,lixun910/pysal,ljwolf/pysal,hasecbinusr/pysal,jlaura/pysal,chhao91/pysal,TaylorOshan/pysal,TaylorOshan/pysal,sjsrey/pysal,pastephens/pysal,jlaura/pysal,lanselin/pysal,TaylorOshan/pysal,badjr/pysal,hasecbinusr/pysal,pastephens/pysal,pedrovma/pysal,lixun910/pysal,schmidtc/pysal,ljwolf/pysal_core,schmidtc/pysal,sjsrey/pysal_core,pysal/pysal,sjsrey/pysal_core,weikang9009/pysal,badjr/pysal,ljwolf/pysal_core,pastephens/pysal,hasecbinusr/pysal,jlaura/pysal