create src directory with all jekyll source code

create nix derivation to generate jekyll static content

src/_includes/author.html

@@ -0,0 +1,9 @@
+<div class="author">
+  <img
+    class="author-avatar"
+    src="{{ site.author.avatar }}"
+    alt="{{ site.author.username }}"
+  />
+  <h2 class="author-name">{{ site.author.name }}</h2>
+  <p class="author-bio">{{ site.author.bio }}</p>
+</div>