feat: make the locations table (plus related content above & below) 2/3 width

app/views/locations/index.html.erb

@@ -11,6 +11,8 @@
 
 <%= render partial: "organisations/headings", locals: { main: @scheme.service_name, sub: nil } %>
 
+<div class="govuk-grid-row">
+  <div class="govuk-grid-column-two-thirds-from-desktop">
     <%= render SubNavigationComponent.new(items: scheme_items(request.path, @scheme.id, "Locations")) %>
 
     <h2 class="govuk-visually-hidden">Locations</h2>
@@ -47,5 +49,7 @@
       <% end %>
     <% end %>
     <%= govuk_button_link_to "Add a location", new_scheme_location_path(scheme_id: @scheme.id), secondary: true %>
+  </div>
+</div>
 
 <%== render partial: "pagy/nav", locals: { pagy: @pagy, item_name: "locations" } %>