Update external users permissions docs

doc/user/permissions.md

@@ -333,7 +333,7 @@ project and should only have access to that project.
 
 External users:
 
-- Cannot create projects (including forks), groups, or snippets.
+- Can only create projects (including forks), subgroups, and snippets within the top-level group to which they belong.
 - Can only access public projects and projects to which they are explicitly granted access,
   thus hiding all other internal or private ones from them (like being
   logged out).