perf: refactor using semantic HTML (#1207)

Fixes #1196

_includes/footer.html

@@ -1,6 +1,7 @@
 <!-- The Footer -->
 
 <footer
+  aria-label="Site Info"
   class="
     d-flex flex-column justify-content-center text-muted
     flex-lg-row justify-content-lg-between align-items-lg-center pb-lg-3
@@ -8,7 +9,7 @@
 >
   <p>
     {{ '©' }}
-    {{ 'now' | date: '%Y' }}
+    <time>{{ 'now' | date: '%Y' }}</time>
     <a href="{{ site.social.links[0] }}">{{ site.social.name }}</a>.
     {% if site.data.locales[include.lang].copyright.brief %}
       <span