Avoid SDG subnavigation link as active when visit help page

This help page can only be accessed from either the help page or the forms.
There is no button in the navigation bar related to this page.
For this reason we do not mark any section of the navigation bar as active
when we are on this page..

app/views/shared/_subnavigation.html.erb

@@ -46,7 +46,7 @@
       <li>
         <%= layout_menu_link_to t("layouts.header.sdg"),
                                 sdg_goals_path,
-                                controller_path.split("/").first == "sdg",
+                                controller_path == "sdg/goals" && action_name != "help",
                                 accesskey: "6" %>
       </li>
     <% end %>