documentation/docstring fix method ParallelSSHClient (ParallelSSH#318)

* Updated ParallelSSHClient docstrings for host_config type Co-authored-by: Stan Rudenko <stanislav.rudenko@okta.com>

Author: rooty0

pssh/clients/native/parallel.py

@@ -80,7 +80,7 @@ def __init__(self, hosts, user=None, password=None, port=22, pkey=None,
  :type pool_size: int
  :param host_config: (Optional) Per-host configuration for cases where
  not all hosts use the same configuration.
- :type host_config: dict
+ :type host_config: list
  :param allow_agent: (Optional) set to False to disable connecting to
  the system's SSH agent.
  :type allow_agent: bool