Adjust the documentation on subgroups

doc/user/group/subgroups/index.md

@@ -75,13 +75,16 @@ structure.
 ## Creating a subgroup
 
 NOTE: **Note:**
-You must be an Owner of a group to create a subgroup. For
-more information check the [permissions table](../../permissions.md#group-members-permissions).
+In order to create a subgroup you must either be an Owner or a Maintainer of the
+group, depending on the group's setting. By default groups allow both Owners and
+Maintainers to create subgroups, but this can be changed by an Owner or
+Administrator to only allow Owners to create subgroups. For more information
+check the [permissions table](../../permissions.md#group-members-permissions).
 For a list of words that are not allowed to be used as group names see the
-[reserved names](../../reserved_names.md).
-Users can always create subgroups if they are explicitly added as an Owner to
-a parent group, even if group creation is disabled by an administrator in their
-settings.
+[reserved names](../../reserved_names.md).  Users can always create subgroups if
+they are explicitly added as an Owner (or Maintainer, if that setting is
+enabled) to a parent group, even if group creation is disabled by an
+administrator in their settings.
 
 To create a subgroup: