DOCSP-20690 directory permissions on install (#591)

* DOCSP-20698 directory permissions on install

* Review feedback

* Review feedback

Author: Dave

source/includes/steps-create-admin-then-enable-authentication.yaml

@@ -7,7 +7,7 @@ pre: |
   Start a standalone :binary:`~bin.mongod` instance without access
   control.
 
-  Open a terminal and run the following command:
+  Open a terminal and run the following command as the ``mongod`` user:
 
 action:
   language: sh
@@ -16,9 +16,19 @@ action:
 post: |
   The :binary:`~bin.mongod` instance in this tutorial uses
   :option:`port 27017 <mongod --port>` and the ``/var/lib/mongodb``
-  data directory. The tutorial assumes that the ``/var/lib/mongodb``
-  directory exists and is the default :setting:`~storage.dbPath`. You
-  may specify a different data directory or port as needed.
+  data directory.
+  
+  The tutorial assumes that the ``/var/lib/mongodb`` directory exists
+  and is the default :setting:`~storage.dbPath`. You may specify a
+  different data directory or port as needed.
+
+  .. tip::
+  
+     When :binary:`mongod` starts, it creates some system files in the
+     ``/var/lib/mongodb`` directory. To ensure the system files have
+     the correct ownership, follow this tutorial as the ``mongod``
+     user. If you start :binary:`mongod` as the ``root`` user you will
+     have to update file ownership later. 
 
 ---
 stepnum: 2