Add pretty natural language, oxford commad, 'and's

agaric/templates/field/field.html.twig

@@ -58,7 +58,8 @@
   <p{{ attributes.removeClass('content') }}>
     <label{{ title_attributes.removeClass('label') }}>{{ label }}</label>
     {% for item in items %}
-      <strong>{{ item.content }}</strong>{% if not loop.last %}, {% endif %}
+      {% if loop.length > 1 and loop.index == loop.length %}and {% endif %}
+      <strong>{{ item.content }}</strong>{% if loop.length > 2 and not loop.last %}, {% endif %}
     {% endfor %}
   </p>
 {% else %}