create access subdirectory

admin-guide/configuration/access/system_access.md

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+# User and admin access
+A list of users and or groups that can access the system. Members of the groups `aaa:admins:` don't need to be members of `aaa::users:` to access a system.
+
+### Regular access
+Access for ActiveDirectory (AD) user accounts or groups that are non Experiment accounts. (See e account section for that)
+```
+aaa::users:
+  - 'muster_h'
+  - '%unx-project_group'
+```
+
+### Sudo access
+To give root access for AD user accounts or groups via sudo.
+```
+aaa::admins:
+  - 'muster_h'
+  - '%unx-project_group'
+```
+