post-cover: enable mardownify

* allows users to add links and stuff #17

assets/css/post-entry.css

@@ -100,3 +100,8 @@
     pointer-events: none;
     width: 100%;
 }
+
+.entry-cover a {
+    color: var(--secondary);
+    box-shadow: 0 1px 0 var(--primary);
+}

layouts/_default/single.html

@@ -33,7 +33,7 @@
     {{- else}}
     <img src="{{ .Permalink -}} {{- .Params.cover.image }}" alt="{{ .Params.cover.alt | plainify }}">
     {{- end}}
-    <p>{{.Params.cover.caption}}</p>
+    <p>{{.Params.cover.caption | markdownify }}</p>
   </figure>
   {{- end }}
   {{- if .Params.ShowToc }}