Add the section class to page views (whole section)

Turns out this is really important to keeping a margin on mobile-sized viewports

agaric/templates/views/views-view--page.html.twig

@@ -32,6 +32,7 @@
 #}
 {%
   set classes = [
+    'section',
     dom_id ? 'js-view-dom-id-' ~ dom_id,
   ]
 %}