add image support: eleventy-img plugin, hero images, responsive picture elements

index.njk

@@ -5,6 +5,11 @@ layout: base.njk
 {%- set latest = collections.columns | first -%}
 {%- if latest %}
 <article class="column-entry">
+  {% if latest.data.hero %}
+  <figure class="column-hero">
+    {% heroImage latest.data.hero, latest.data.heroAlt or latest.data.title %}
+  </figure>
+  {% endif %}
   <header class="column-header">
     <h1><a href="{{ latest.url }}">{{ latest.data.title }}</a></h1>
     <time datetime="{{ latest.date | isoDate }}">{{ latest.date | readableDate }}</time>