chore: remove <h1> element from site title

Author: kungfux

_includes/sidebar.html

@@ -11,9 +11,9 @@
       {%- endif -%}
     </a>
 
-    <h1 class="site-title">
+    <p class="site-title">
       <a href="{{ '/' | relative_url }}">{{ site.title }}</a>
-    </h1>
+    </p>
     <p class="site-subtitle fst-italic mb-0">{{ site.tagline }}</p>
   </header>
   <!-- .profile-wrapper -->