Fix rtd link on readme (#1943)
Fix rtd link on readme (#1943)


shoyer/xray,jhamman/xarray,pydata/xarray,jhamman/xray,pydata/xarray,markelg/xray,jcmgray/xarray,shoyer/xarray,markelg/xray,jhamman/xarray,xray/xray,chunweiyuan/xarray,markelg/xray,pydata/xarray,shoyer/xarray,jhamman/xarray