Document Account Admin role in docs/guide/people.

docs/guide/people.md

@@ -8,7 +8,7 @@ Roles can be "managed" or "unmanaged." The permissions of managed roles are
 controlled by modules and cannot be modified through the UI. Unmanaged roles
 can be added/edited through the UI.
 
-Three managed roles are provided with farmOS:
+Three default managed roles are provided with farmOS:
 
 - **Manager** - Has access to everything in farmOS. They can create, edit, and
   delete records, and they can change configuration settings.
@@ -22,6 +22,12 @@ Three managed roles are provided with farmOS:
 
 These roles can be disabled by uninstalling the "Default Roles" module.
 
+The "farmOS Account Admin Role" module provides another optional managed role
+called **Account Admin**, which has permission to add/edit/remove other users.
+This is useful in situations where an instance administrator wants to give
+someone the ability to set up other accounts, without giving them full admin
+access.
+
 Permissions for managed roles cannot be modified through the UI. This is not
 generally an issue since the provided roles have been carefully tailored to
 work for most applications. In some cases, you may want to further customize