DOC: update develop doc with conda option (#5939)
DOC: update develop doc with conda option (#5939)

* update develop doc with conda option

* python -m pip

* add git clone info

* rebase

jakirkham/dask,ContinuumIO/dask,mrocklin/dask,dask/dask,mrocklin/dask,blaze/dask,ContinuumIO/dask,blaze/dask,dask/dask,jakirkham/dask