feat: Add soungbook example

- Add songbook to demo
- Add macro for song
- Add style module

source/templates/hippie/macros/_song.njk

@@ -0,0 +1,12 @@
+{% macro simple(index, data, content) %}
+  <article class="songbook_song">
+    <header>
+      <h2>{{ data.title }}</h2>
+      <h6>{{ data.releaseDate }}</h6>
+      <p>{{ data.description }}</p>
+    </header>
+    {# <pre class="pre_code"><code>{{ content }}</code></pre> #}
+    {{ content | safe }}
+    <footer>{{ index }}</footer>
+  </article>
+{% endmacro %}