update docs for Moran rate and local moran rate
update docs for Moran rate and local moran rate

lixun910/pysal,pysal/pysal,weikang9009/pysal,lixun910/pysal,pedrovma/pysal,ljwolf/pysal,ljwolf/pysal,ljwolf/pysal,sjsrey/pysal,lixun910/pysal,lanselin/pysal