add dataframe creation docs
add dataframe creation docs

ContinuumIO/dask,PhE/dask,jakirkham/dask,pombredanne/dask,freeman-lab/dask,ssanderson/dask,ssanderson/dask,mraspaud/dask,gameduell/dask,vikhyat/dask,jayhetee/dask,mikegraham/dask,blaze/dask,simudream/dask,clarkfitzg/dask,blaze/dask,jakirkham/dask,PhE/dask,jcrist/dask,vikhyat/dask,mrocklin/dask,wiso/dask,cpcloud/dask,jayhetee/dask,cowlicks/dask,mrocklin/dask,ContinuumIO/dask,dask/dask,mraspaud/dask,pombredanne/dask,freeman-lab/dask,clarkfitzg/dask,chrisbarber/dask,simudream/dask,jcrist/dask,wiso/dask,dask/dask