DOC: configure sshcluster instructions (#8181)
DOC: configure sshcluster instructions (#8181)

* DOC: configure sshcluster instructions

* DOC: add keyless info

Co-authored-by: Jim Crist-Harif <72596308b98cc49fbcb30d2b7b0c9440cb6daa88@users.noreply.github.com>
dask/dask,dask/dask,blaze/dask,blaze/dask,jakirkham/dask,jakirkham/dask