Update porting_guide_2.5.rst

A fix to a minor typo. ("Previouslu" -> "Previously")

 label: docsite_pr

docs/docsite/rst/porting_guides/porting_guide_2.5.rst

@@ -181,7 +181,7 @@ Shell plugins have been migrated to the new plugin configuration framework. It i
 
 For example, ``system_temps`` is a new setting that allows you to control what Ansible will consider a 'system temporary dir'. This is used when escalating privileges for a non-administrative user. Previously this was hardcoded to '/tmp', which some systems cannot use for privilege escalation. This setting now defaults to ``[ '/var/tmp', '/tmp']``.
 
-Another new setting is ``admin_users`` which allows you to specify a list of users to be considered 'administrators'. Previouslu this was hardcoded to ``root``. It now it defaults to ``[root, toor, admin]``.  This information is used when choosing between your ``remote_temp`` and ``system_temps`` directory.
+Another new setting is ``admin_users`` which allows you to specify a list of users to be considered 'administrators'. Previously this was hardcoded to ``root``. It now it defaults to ``[root, toor, admin]``.  This information is used when choosing between your ``remote_temp`` and ``system_temps`` directory.
 
 For a full list, check the shell plugin you are using, the default shell plugin is ``sh``.