Theme: Add support for content above posts-archive layout

Similar to the "group" layout as used on API pages.

Author: Krinkle

_layouts/posts-archive.html

@@ -10,6 +10,7 @@
 {%- assign prev_year = false -%}
 <div class="posts content">
 	<h1>{{ page.title }}</h1>
+	{{ content }}
 	{% for post in posts -%}
 		{%- assign post_year = post.date | date: '%Y' -%}
 		{%- if post_year != prev_year -%}