Update single_host_deployment.rst

* Initialize your node configuration: create a self-signed certificate 

  for $ESGF_HOSTNAME and populate the $ESGF_CONFIG directory with initial content::

  Note: if you are on a Mac, ensure **gtar** and **xz** utilities are installed before running the :code:`esgf_node_init.sh` script::

    ./scripts/esgf_node_init.sh

    ls -l $ESGF_CONFIG