add private method _run_playbook_proc to documentation

build-docs.sh

+#!/bin/sh
+set -o errexit
+set -o nounset
+
 pip install -r requirements.txt
 pip install -e .
 

docs/source/module/playbook.rst

@@ -3,4 +3,5 @@
 
 .. automodule:: lso.playbook
    :members:
+   :private-members:
    :show-inheritance: