Update 0.5.2 release notes

Author: ellmetha

docs/docs/the-marten-project/release-notes/0.5.2.md

@@ -12,3 +12,4 @@ _Under development._
 * Fix non-existing error when the [`new`](../../development/reference/management-commands.md#new) management command was used to generate an app structure with the `--with-auth` option.
 * Fix missing "emails" folder requirement in projects generated with the [`new`](../../development/reference/management-commands.md#new) management command.
 * Fix how nested routes are displayed when invoking the [`routes`](../../development/reference/management-commands.md#routes) management command.
+* Fix settings namespace generation for top-level `Settings` settings classes.