add img to post layout

_includes/layouts/post.njk

@@ -7,4 +7,6 @@ layout: page.njk
 <p>Posted on <time datetime="{{ date-posted }}">{{ date-posted | htmlDateString }}</time></p>
 <p>Updated on <time datetime="{{ date-updated }}">{{ date-updated | htmlDateString }}</time></p>
 
+<img src="{{ image.src }}" alt="{{ image.alt }}">
+
 {{ content | safe }}